自从上次 Ubuntu 18.04 更新（我使用自动软件更新程序）以来，上周的某个时间，到我的路由器（Telekom Speedport Smart 3）的以太网连接不再工作。
我检查了电缆，在安装在同一盒子上的另一个操作系统上使用它没有任何问题。
当我尝试从 Ubuntu 18.04 连接时，我的路由器日志显示 DHCP 连接尝试失败，遗憾的是没有更多详细信息。
这是我尝试连接时来自 NetworkManager 的日志：
$ journalctl -u NetworkManager
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8154] device (enp3s0): Activation: starting connection 'Wired connection 1' (aae30bcd-f48c-3355-b8ea-0f85b41ceda7)
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8155] audit: op="connection-activate" uuid="aae30bcd-f48c-3355-b8ea-0f85b41ceda7" name="Wired connection 1" pid=14866 uid=1000 result="success"
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8159] device (enp3s0): state change: disconnected -> prepare (reason 'none', sys-iface-state: 'managed')
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8162] manager: NetworkManager state is now CONNECTING
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8168] device (enp3s0): state change: prepare -> config (reason 'none', sys-iface-state: 'managed')
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8179] device (enp3s0): state change: config -> ip-config (reason 'none', sys-iface-state: 'managed')
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8183] dhcp4 (enp3s0): activation: beginning transaction (timeout in 45 seconds)
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8206] dhcp4 (enp3s0): dhclient started with pid 22206
Sep 18 11:52:59 Oland dhclient[22206]: DHCPREQUEST of 192.168.2.102 on enp3s0 to 255.255.255.255 port 67 (xid=0x314975af)
Sep 18 11:52:59 Oland dhclient[22206]: DHCPNAK from 192.168.2.1 (xid=0xaf754931)
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8588] dhcp4 (enp3s0): state changed unknown -> expire
Sep 18 11:52:59 Oland NetworkManager[1325]: <info> [1568800379.8616] dhcp4 (enp3s0): state changed expire -> unknown
Sep 18 11:52:59 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 3 (xid=0x7178e0b)
Sep 18 11:53:01 Oland NetworkManager[1325]: <info> [1568800381.6610] dhcp6 (enp3s0): activation: beginning transaction (timeout in 45 seconds)
Sep 18 11:53:01 Oland NetworkManager[1325]: <info> [1568800381.6627] dhcp6 (enp3s0): dhclient started with pid 22223
Sep 18 11:53:02 Oland dhclient[22223]: XMT: Info-Request on enp3s0, interval 1090ms.
Sep 18 11:53:02 Oland dhclient[22223]: RCV: Reply message on enp3s0 from fe80::1.
Sep 18 11:53:02 Oland NetworkManager[1325]: <info> [1568800382.0790] dhcp6 (enp3s0): nameserver 'fe80::1'
Sep 18 11:53:02 Oland NetworkManager[1325]: <info> [1568800382.0791] dhcp6 (enp3s0): state changed unknown -> bound
Sep 18 11:53:02 Oland NetworkManager[1325]: <info> [1568800382.0807] dhcp6 (enp3s0): client pid 22223 exited with status 0
Sep 18 11:53:02 Oland NetworkManager[1325]: <info> [1568800382.0807] dhcp6 (enp3s0): state changed bound -> done
Sep 18 11:53:02 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 6 (xid=0x7178e0b)
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1215] device (enp3s0): state change: ip-config -> ip-check (reason 'none', sys-iface-state: 'managed')
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1227] device (enp3s0): state change: ip-check -> secondaries (reason 'none', sys-iface-state: 'managed')
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1235] device (enp3s0): state change: secondaries -> activated (reason 'none', sys-iface-state: 'managed')
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1238] manager: NetworkManager state is now CONNECTED_LOCAL
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1292] manager: NetworkManager state is now CONNECTED_SITE
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1293] policy: set 'Wired connection 1' (enp3s0) as default for IPv6 routing and DNS
Sep 18 11:53:03 Oland NetworkManager[1325]: <info> [1568800383.1298] device (enp3s0): Activation: successful, device activated.
Sep 18 11:53:08 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 6 (xid=0x7178e0b)
Sep 18 11:53:14 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 9 (xid=0x7178e0b)
Sep 18 11:53:23 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 13 (xid=0x7178e0b)
Sep 18 11:53:33 Oland NetworkManager[1325]: <info> [1568800413.6583] connectivity: (enp3s0) timed out
Sep 18 11:53:36 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 11 (xid=0x7178e0b)
Sep 18 11:53:47 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 20 (xid=0x7178e0b)
Sep 18 11:54:07 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 11 (xid=0x7178e0b)
Sep 18 11:54:18 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 11 (xid=0x7178e0b)
Sep 18 11:54:29 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 11 (xid=0x7178e0b)
Sep 18 11:54:40 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 12 (xid=0x7178e0b)
Sep 18 11:54:52 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 13 (xid=0x7178e0b)
Sep 18 11:54:57 Oland NetworkManager[1325]: <info> [1568800497.6581] connectivity: (enp3s0) timed out
Sep 18 11:55:05 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 10 (xid=0x7178e0b)
Sep 18 11:55:15 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 19 (xid=0x7178e0b)
Sep 18 11:55:34 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 10 (xid=0x7178e0b)
Sep 18 11:55:44 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 7 (xid=0x7178e0b)
Sep 18 11:55:51 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 16 (xid=0x7178e0b)
Sep 18 11:56:07 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 16 (xid=0x7178e0b)
Sep 18 11:56:23 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 11 (xid=0x7178e0b)
Sep 18 11:56:34 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 12 (xid=0x7178e0b)
Sep 18 11:56:46 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 13 (xid=0x7178e0b)
Sep 18 11:56:59 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 16 (xid=0x7178e0b)
Sep 18 11:57:15 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 15 (xid=0x7178e0b)
Sep 18 11:57:30 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 21 (xid=0x7178e0b)
Sep 18 11:57:51 Oland dhclient[22206]: DHCPDISCOVER on enp3s0 to 255.255.255.255 port 67 interval 9 (xid=0x7178e0b)
Sep 18 11:58:00 Oland dhclient[22206]: No DHCPOFFERS received.
Sep 18 11:58:00 Oland dhclient[22206]: Trying recorded lease 192.168.2.201
Sep 18 11:58:00 Oland NetworkManager[1325]: <info> [1568800680.9260] dhcp4 (enp3s0): state changed unknown -> timeout
Sep 18 11:58:00 Oland NetworkManager[1325]: <info> [1568800680.9583] dhcp4 (enp3s0): canceled DHCP transaction, DHCP client pid 22206
Sep 18 11:58:00 Oland NetworkManager[1325]: <info> [1568800680.9584] dhcp4 (enp3s0): state changed timeout -> done
我曾尝试在有线连接设置中禁用 Ipv6，但这并没有改变任何东西，所以我再次将其设置为“自动”。
有什么想法可以进一步挖掘吗？是否有任何已知的最新更新可能与此有关？我想尝试应用较新的系统更新，看看这是否能解决问题，但由于我在那台机器上处于离线状态，我不知道如何轻松做到这一点。如何在没有连接的机器上应用最近的系统更新？
谢谢您的指点。