我使用 Debian Jessie 8.2 并且使用 3G 连接华为MU709 Mini PCIe。
3G 连接工作正常，但 24 小时后连接断开且无法重新连接。如果我重新启动计算机，连接将再次工作。
我的猜测是，我的 ISP 在 24 小时后给了我一个新的 IP 地址，但不知何故我的系统无法处理它。
如何在不重新启动的情况下重新连接 3G 连接？
我已经尝试过以下命令：
sudo service network-manager restart
并且：
dhclient -r eth0
dhclient eth0
编辑1：
journalctl并 grep 我的连接名称的结果( SFR)
sept. 22 17:58:19 ark1 NetworkManager[512]: <info> Policy set 'SFR Web / Prepaid 1' (eth0) as default for IPv4 routing and DNS.
sept. 23 18:17:07 ark1 NetworkManager[9446]: <info> new connection /etc/NetworkManager/system-connections/SFR Web * Prepaid 1
sept. 23 18:17:08 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR Web / Prepaid 1'.
sept. 23 18:17:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR Web / Prepaid 1'
sept. 23 18:17:53 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR Web / Prepaid 1'
sept. 23 18:17:53 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR Web / Prepaid 1'.
sept. 23 18:17:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR Web / Prepaid 1'
sept. 23 18:18:03 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR Web / Prepaid 1'
sept. 23 18:18:03 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR Web / Prepaid 1'.
sept. 23 18:18:03 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR Web / Prepaid 1'
sept. 23 18:18:13 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR Web / Prepaid 1'
正如您所看到的，sept 22 at time 17:18这是计算机启动的时间。大约 24 小时后，无法重新连接。
另外我应该提到有一个脚本来运行命令：
sudo service network-manager restart
如果计算机无法 ping 通服务器，即连接丢失。
编辑2：journalctl当系统尝试重新连接时 添加更多信息：
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR'.
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR'
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) scheduled...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) started...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) complete.
sept. 23 23:52:53 ark1 ModemManager[518]: <info> Simple connect started...
sept. 23 23:52:53 ark1 ModemManager[518]: <info> Simple connect state (4/8): Wait to get fully enabled
sept. 23 23:52:53 ark1 ModemManager[518]: <info> Simple connect state (5/8): Register
sept. 23 23:52:53 ark1 ModemManager[518]: <info> Simple connect state (6/8): Bearer
sept. 23 23:52:53 ark1 ModemManager[518]: <info> Simple connect state (7/8): Connect
sept. 23 23:52:53 ark1 ModemManager[518]: <info> Simple connect state (8/8): All done
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) scheduled...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) starting...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: prepare -> config (reason 'none') [40 50 0]
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) successful.
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 3 of 5 (IP Configure Start) scheduled.
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) complete.
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 3 of 5 (IP Configure Start) started...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: config -> ip-config (reason 'none') [50 70 0]
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds)
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> dhclient started with pid 13212
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv6 Configure Timeout) scheduled...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 3 of 5 (IP Configure Start) complete.
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv6 Configure Timeout) started...
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv6 Configure Timeout) complete.
sept. 23 23:52:53 ark1 NetworkManager[9446]: <info> (eth0): DHCPv4 state changed nbi -> preinit
sept. 23 23:52:53 ark1 dhclient[13212]: DHCPREQUEST on eth0 to 255.255.255.255 port 67
sept. 23 23:52:59 ark1 dhclient[13212]: DHCPREQUEST on eth0 to 255.255.255.255 port 67
sept. 23 23:53:09 ark1 dhclient[13212]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 5
sept. 23 23:53:14 ark1 dhclient[13212]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
sept. 23 23:53:22 ark1 dhclient[13212]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 10
sept. 23 23:53:32 ark1 dhclient[13212]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
sept. 23 23:53:38 ark1 NetworkManager[9446]: <warn> (eth0): DHCPv4 request timed out.
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> (eth0): canceled DHCP transaction, DHCP client pid 13212
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) scheduled...
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) started...
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: ip-config -> failed (reason 'ip-config-unavailable') [70 120 5]
sept. 23 23:53:38 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR'
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) complete.
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: failed -> disconnected (reason 'none') [120 30 0]
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> (ttyUSB0): deactivating device (reason 'none') [0]
sept. 23 23:53:38 ark1 avahi-daemon[528]: Withdrawing address record for 169.254.1.156 on eth0.
sept. 23 23:53:38 ark1 avahi-daemon[528]: Leaving mDNS multicast group on interface eth0.IPv4 with address 169.254.1.156.
sept. 23 23:53:38 ark1 avahi-daemon[528]: Interface eth0.IPv4 no longer relevant for mDNS.
sept. 23 23:53:38 ark1 dhclient[11114]: receive_packet failed on eth0: Network is down
sept. 23 23:53:38 ark1 ModemManager[518]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connected -> disconnecting)
sept. 23 23:53:38 ark1 ModemManager[518]: <warn> Couldn't find associated cdc-wdm port for 'net/eth0'
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR'.
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR'
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) scheduled...
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) started...
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) complete.
sept. 23 23:53:38 ark1 NetworkManager[9446]: <info> (ttyUSB0): modem state changed, 'connected' --> 'disconnecting' (reason: user-requested)
sept. 23 23:53:38 ark1 avahi-autoipd(eth0)[13202]: SIOCSIFFLAGS failed: Operation not permitted
sept. 23 23:53:38 ark1 avahi-autoipd(eth0)[13202]: Callout STOP, address 169.254.1.156 on interface eth0
sept. 23 23:53:39 ark1 ModemManager[518]: <info> Simple connect started...
sept. 23 23:53:39 ark1 ModemManager[518]: <info> Simple connect state (4/8): Wait to get fully enabled
sept. 23 23:53:39 ark1 avahi-autoipd(eth0)[13203]: client: RTNETLINK answers: No such process
sept. 23 23:53:39 ark1 avahi-autoipd(eth0)[13203]: client: RTNETLINK answers: Cannot assign requested address
sept. 23 23:53:39 ark1 avahi-autoipd(eth0)[13203]: Script execution failed with return value 2
sept. 23 23:53:48 ark1 NetworkManager[9446]: <warn> (ttyUSB0) failed to connect modem: Too much time waiting to get to a final state
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: prepare -> failed (reason '(null)') [40 120 1]
sept. 23 23:53:48 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR'
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: failed -> disconnected (reason 'none') [120 30 0]
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> (ttyUSB0): deactivating device (reason 'none') [0]
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR'.
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR'
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) scheduled...
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) started...
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
sept. 23 23:53:48 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) complete.
sept. 23 23:53:48 ark1 ModemManager[518]: <info> Simple connect started...
sept. 23 23:53:48 ark1 ModemManager[518]: <info> Simple connect state (4/8): Wait to get fully enabled
sept. 23 23:53:58 ark1 NetworkManager[9446]: <warn> (ttyUSB0) failed to connect modem: Too much time waiting to get to a final state
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: prepare -> failed (reason '(null)') [40 120 1]
sept. 23 23:53:58 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR'
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: failed -> disconnected (reason 'none') [120 30 0]
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> (ttyUSB0): deactivating device (reason 'none') [0]
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR'.
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR'
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) scheduled...
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) started...
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
sept. 23 23:53:58 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) complete.
sept. 23 23:53:58 ark1 ModemManager[518]: <info> Simple connect started...
sept. 23 23:53:58 ark1 ModemManager[518]: <info> Simple connect state (4/8): Wait to get fully enabled
sept. 23 23:54:08 ark1 NetworkManager[9446]: <warn> (ttyUSB0) failed to connect modem: Too much time waiting to get to a final state
sept. 23 23:54:08 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: prepare -> failed (reason '(null)') [40 120 1]
sept. 23 23:54:08 ark1 NetworkManager[9446]: <info> Disabling autoconnect for connection 'SFR'.
sept. 23 23:54:08 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR'
sept. 23 23:54:08 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: failed -> disconnected (reason 'none') [120 30 0]
sept. 23 23:54:08 ark1 NetworkManager[9446]: <info> (ttyUSB0): deactivating device (reason 'none') [0]
sept. 23 23:54:39 ark1 ModemManager[518]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: state changed (disconnecting -> connected)
sept. 23 23:54:39 ark1 NetworkManager[9446]: <info> (ttyUSB0): modem state changed, 'disconnecting' --> 'connected' (reason: user-requested)
sept. 23 23:55:31 ark1 noip2[1786]: Can't get our visible IP address from ip1.dynupdate.no-ip.com
sept. 23 23:55:50 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
sept. 23 23:55:50 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:55:50 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:55:54 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
sept. 23 23:55:54 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:55:54 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:56:02 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
sept. 23 23:56:02 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:56:02 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:56:13 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 10
sept. 23 23:56:13 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:56:13 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:56:23 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
sept. 23 23:56:23 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:56:23 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:56:34 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
sept. 23 23:56:34 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:56:34 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:56:43 ark1 dhclient[11114]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 8
sept. 23 23:56:43 ark1 dhclient[11114]: send_packet: Network is down
sept. 23 23:56:43 ark1 dhclient[11114]: dhclient.c:1966: Failed to send 300 byte long packet over eth0 interface.
sept. 23 23:56:51 ark1 dhclient[11114]: No DHCPOFFERS received.
sept. 23 23:56:51 ark1 dhclient[11114]: No working leases in persistent database - sleeping.
sept. 23 23:56:51 ark1 avahi-autoipd(eth0)[13229]: Found user 'avahi-autoipd' (UID 109) and group 'avahi-autoipd' (GID 118).
sept. 23 23:56:51 ark1 avahi-autoipd(eth0)[13229]: Successfully called chroot().
sept. 23 23:56:51 ark1 avahi-autoipd(eth0)[13229]: Successfully dropped root privileges.
sept. 23 23:56:51 ark1 avahi-autoipd(eth0)[13229]: Starting with address 169.254.1.156
sept. 23 23:56:57 ark1 avahi-autoipd(eth0)[13229]: Callout BIND, address 169.254.1.156 on interface eth0
sept. 23 23:56:57 ark1 avahi-daemon[528]: Joining mDNS multicast group on interface eth0.IPv4 with address 169.254.1.156.
sept. 23 23:56:57 ark1 avahi-daemon[528]: New relevant interface eth0.IPv4 for mDNS.
sept. 23 23:56:57 ark1 avahi-daemon[528]: Registering new address record for 169.254.1.156 on eth0.IPv4.
sept. 23 23:57:01 ark1 avahi-autoipd(eth0)[13229]: Successfully claimed IP address 169.254.1.156
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR'.
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) starting connection 'SFR'
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) scheduled...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) started...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: disconnected -> prepare (reason 'none') [30 40 0]
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 1 of 5 (Device Prepare) complete.
sept. 23 23:59:08 ark1 ModemManager[518]: <info> Simple connect started...
sept. 23 23:59:08 ark1 ModemManager[518]: <info> Simple connect state (4/8): Wait to get fully enabled
sept. 23 23:59:08 ark1 ModemManager[518]: <info> Simple connect state (5/8): Register
sept. 23 23:59:08 ark1 ModemManager[518]: <info> Simple connect state (6/8): Bearer
sept. 23 23:59:08 ark1 ModemManager[518]: <info> Simple connect state (7/8): Connect
sept. 23 23:59:08 ark1 ModemManager[518]: <info> Simple connect state (8/8): All done
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) scheduled...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) starting...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: prepare -> config (reason 'none') [40 50 0]
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) successful.
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 3 of 5 (IP Configure Start) scheduled.
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 2 of 5 (Device Configure) complete.
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 3 of 5 (IP Configure Start) started...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: config -> ip-config (reason 'none') [50 70 0]
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (eth0) Beginning DHCPv4 transaction (timeout in 45 seconds)
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> dhclient started with pid 13236
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv6 Configure Timeout) scheduled...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 3 of 5 (IP Configure Start) complete.
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv6 Configure Timeout) started...
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv6 Configure Timeout) complete.
sept. 23 23:59:08 ark1 NetworkManager[9446]: <info> (eth0): DHCPv4 state changed nbi -> preinit
sept. 23 23:59:09 ark1 dhclient[13236]: DHCPREQUEST on eth0 to 255.255.255.255 port 67
sept. 23 23:59:17 ark1 dhclient[13236]: DHCPREQUEST on eth0 to 255.255.255.255 port 67
sept. 23 23:59:31 ark1 dhclient[13236]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3
sept. 23 23:59:34 ark1 dhclient[13236]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4
sept. 23 23:59:38 ark1 dhclient[13236]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 11
sept. 23 23:59:49 ark1 dhclient[13236]: DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9
sept. 23 23:59:53 ark1 NetworkManager[9446]: <warn> (eth0): DHCPv4 request timed out.
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> (eth0): canceled DHCP transaction, DHCP client pid 13236
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) scheduled...
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) started...
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: ip-config -> failed (reason 'ip-config-unavailable') [70 120 5]
sept. 23 23:59:53 ark1 NetworkManager[9446]: <warn> Activation (ttyUSB0) failed for connection 'SFR'
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) complete.
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): device state change: failed -> disconnected (reason 'none') [120 30 0]
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): deactivating device (reason 'none') [0]
sept. 23 23:59:53 ark1 avahi-daemon[528]: Withdrawing address record for 169.254.1.156 on eth0.
sept. 23 23:59:53 ark1 avahi-daemon[528]: Leaving mDNS multicast group on interface eth0.IPv4 with address 169.254.1.156.
sept. 23 23:59:53 ark1 avahi-daemon[528]: Interface eth0.IPv4 no longer relevant for mDNS.
sept. 23 23:59:53 ark1 dhclient[11114]: receive_packet failed on eth0: Network is down
sept. 23 23:59:53 ark1 avahi-autoipd(eth0)[13229]: SIOCSIFFLAGS failed: Operation not permitted
sept. 23 23:59:53 ark1 avahi-autoipd(eth0)[13229]: Callout STOP, address 169.254.1.156 on interface eth0
sept. 23 23:59:53 ark1 ModemManager[518]: <info> Modem /org/freedesktop/ModemManager1/Modem/0: state changed (connected -> disconnecting)
sept. 23 23:59:53 ark1 ModemManager[518]: <warn> Couldn't find associated cdc-wdm port for 'net/eth0'
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> (ttyUSB0): modem state changed, 'connected' --> 'disconnecting' (reason: user-requested)
sept. 23 23:59:53 ark1 NetworkManager[9446]: <info> Auto-activating connection 'SFR'.
我也尝试了 Wouter Verhelst 的答案，但没有成功：
systemctl restart ModemManager
编辑3：
NetworkManager.conf文件：
[main] plugins=ifupdown,keyfile
[ifupdown] managed=false
编辑4：
$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
link/ether 00:0b:ab:9d:7c:20 brd ff:ff:ff:ff:ff:ff
3: eth2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
link/ether 00:0b:ab:9c:29:84 brd ff:ff:ff:ff:ff:ff
4: eth3: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
link/ether 00:0b:ab:9c:29:85 brd ff:ff:ff:ff:ff:ff
5: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 00:1e:10:1f:00:00 brd ff:ff:ff:ff:ff:ff
编辑5：
当连接工作时：
ps ax | grep 'pppd' | grep -v 'grep'
不输出任何内容。
编辑6：
~$ mmcli -m 0
/org/freedesktop/ModemManager1/Modem/0 (device id 'cd32f4358dd82cdb976fcc9df44df11737726856')
-------------------------
Hardware | manufacturer: 'Huawei Technologies Co., Ltd.'
| model: 'MU709s-2'
| revision: '11.651.67.00.00'
| supported: 'gsm-umts'
| current: 'gsm-umts'
| equipment id: '864881021266208'
-------------------------
System | device: '/sys/devices/pci0000:00/0000:00:1d.7/usb5/5-6'
| drivers: 'option1, cdc_ether'
| plugin: 'Huawei'
| primary port: 'ttyUSB0'
| ports: 'ttyUSB0 (at), ttyUSB2 (at), ttyUSB3 (at), eth0 (net)'
-------------------------
Numbers | own : 'unknown'
-------------------------
Status | lock: 'none'
| unlock retries: 'sim-pin (3), sim-pin2 (3), sim-puk (10), sim-puk2 (10)'
| state: 'connected'
| power state: 'on'
| access tech: 'umts'
| signal quality: '32' (recent)
-------------------------
Modes | supported: 'allowed: 2g, 3g; preferred: none
| allowed: 2g, 3g; preferred: 2g
| allowed: 2g, 3g; preferred: 3g
| allowed: 2g; preferred: none
| allowed: 3g; preferred: none'
| current: 'allowed: 2g, 3g; preferred: 3g'
-------------------------
Bands | supported: 'unknown'
| current: 'unknown'
-------------------------
IP | supported: 'ipv4'
-------------------------
3GPP | imei: '864881021266208'
| enabled locks: 'none'
| operator id: '20810'
| operator name: 'F SFR'
| subscription: 'unknown'
| registration: 'home'
-------------------------
SIM | path: '/org/freedesktop/ModemManager1/SIM/0'
-------------------------
Bearers | paths: '/org/freedesktop/ModemManager1/Bearer/0'
最后编辑：
我找到的唯一解决方案是将 MU709 调制解调器更改为 VIA EMIO-2550。我的 VIA 没有连接问题。
答案1
您确定您的 GSM 连接使用eth0接口吗？大多数情况下是这样ppp0，wwan0或者usb0使用最新的 MBIM 协议。eth0与移动宽带的接口相当罕见。
您的 GMS 卡似乎使用该/dev/ttyUSB0接口来连接到实际的移动宽带网络，pppd并通过该eth0接口将该连接传输到专用 DHCP 网络。 169.254.xx IP范围是链路本地地址，用于提供简单的DHCP连接。
因此，如果 NetworkManager 无法拨打 pppd 连接，移动宽带将不可用。
根据我的经验，如果您已连接，ISP 永远不会更改 IP 地址，并且每次重新连接后他们总是会提供不同的 IP 地址，至少对于移动宽带而言是这样。
现在发生了什么（再次，我的个人经验）调制解调器挂了，由于这是一个 mini PCIe 卡，您不能简单地插拔它。这里是老式的在命令很有用。
尝试将端口与您最喜欢的串行连接应用程序连接，/dev/ttyUSB0例如Putty，，，，等等。我使用的是原始的.minicomcutecomcubusybox microcombusybox microcom
nmcli radio wwan off
sudo busybox microcom -t 10000 /dev/ttyUSB0
把这些 AT 命令放在那里。
ATZ
AT+CFUN=0
等待 10 秒。并再次连接。
sudo busybox microcom -t 10000 /dev/ttyUSB0
AT+CFUN=1
现在退出并再次尝试通过 NetworkManager 小程序进行连接。
当移动宽带连接处于活动状态时，运行以下命令并请更新您的问题。
ps ax | grep 'pppd' | grep -v 'grep'
您的 GSM 卡很棒，有很多高级功能，遗憾的是无法正常工作。
答案2
NetworkManager 参与处理 3G 调制解调器，但只是一小部分。与调制解调器对话的实际程序称为ModemManager。我注意到我的笔记本电脑有时也会失去连接，然后
systemctl restart ModemManager
足够了。
答案3
日志输出journalctl并不清楚导致这种情况发生的原因。我建议按顺序执行以下操作：
1）。发生这种情况时，请尝试手动设置界面：
ifconfig eth0 up
或者，如果您尚未ifconfig安装，可以使用以下命令执行此操作ip：
ip link set dev eth0 up
2）。如果这没有帮助，请检查/var/log/syslog相关消息。
如果我必须做出有根据的猜测，这是与调制解调器本身相关的配置问题。您能否发布 NetworkManager 配置文件本身，并删除其中可能包含的任何敏感信息？