我最近全新安装了 Ubuntu 18.04。
但现在我的网络连接会随机断开。无论是使用以太网还是使用 WLAN 连接，都会发生这种情况。我尝试了两种不同的 WLAN 电缆，之前都运行正常。
输出tail -f /var/log/kern.log为：
Apr 28 15:48:49 i7 kernel: [ 408.161936] e1000e: enp0s31f6 NIC Link is Down
Apr 28 15:48:59 i7 kernel: [ 418.117433] e1000e: enp0s31f6 NIC Link is Up 100 Mbps Full Duplex, Flow Control: Rx/Tx
Apr 28 15:48:59 i7 kernel: [ 418.117440] e1000e 0000:00:1f.6 enp0s31f6: 10/100 speed: disabling TSO
lspci：
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Host Bridge/DRAM Registers (rev 07)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 530 (rev 06)
00:14.0 USB controller: Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller (rev 31)
00:16.0 Communication controller: Intel Corporation 100 Series/C230 Series Chipset Family MEI Controller #1 (rev 31)
00:17.0 SATA controller: Intel Corporation Q170/Q150/B150/H170/H110/Z170/CM236 Chipset SATA Controller [AHCI Mode] (rev 31)
00:1b.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #17 (rev f1)
00:1b.2 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #19 (rev f1)
00:1c.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #1 (rev f1)
00:1d.0 PCI bridge: Intel Corporation 100 Series/C230 Series Chipset Family PCI Express Root Port #9 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Z170 Chipset LPC/eSPI Controller (rev 31)
00:1f.2 Memory controller: Intel Corporation 100 Series/C230 Series Chipset Family Power Management Controller (rev 31)
00:1f.3 Audio device: Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller (rev 31)
00:1f.4 SMBus: Intel Corporation 100 Series/C230 Series Chipset Family SMBus (rev 31)
00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (2) I219-V (rev 31)
02:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8192CE PCIe Wireless Network Adapter (rev 01)
03:00.0 USB controller: ASMedia Technology Inc. ASM1142 USB 3.1 Host Controller
04:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd NVMe SSD Controller SM951/PM951 (rev 01)
ifconfig -a：
enp0s31f6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.178.93 netmask 255.255.255.0 broadcast 192.168.178.255
inet6 fe80::5e03:8c96:eeaa:979a prefixlen 64 scopeid 0x20<link>
ether 34:97:f6:8e:9c:e2 txqueuelen 1000 (Ethernet)
RX packets 106315 bytes 75284075 (75.2 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 696757 bytes 985446361 (985.4 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
device interrupt 16 memory 0xf7300000-f7320000
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1000 (Local Loopback)
RX packets 7792 bytes 7648787 (7.6 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 7792 bytes 7648787 (7.6 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
wlp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.178.94 netmask 255.255.255.0 broadcast 192.168.178.255
inet6 fe80::3ea3:7811:db83:317 prefixlen 64 scopeid 0x20<link>
ether 14:da:e9:f1:a6:6d txqueuelen 1000 (Ethernet)
RX packets 438 bytes 139294 (139.2 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 77 bytes 12333 (12.3 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
sudo lshw -C network：
*-network
description: Wireless interface
product: RTL8192CE PCIe Wireless Network Adapter
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:02:00.0
logical name: wlp2s0
version: 01
serial: 14:da:e9:f1:a6:6d
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=rtl8192ce driverversion=4.18.0-17-generic firmware=N/A ip=192.168.178.94 latency=0 link=yes multicast=yes wireless=IEEE 802.11
resources: irq:18 ioport:e000(size=256) memory:f7200000-f7203fff
*-network
description: Ethernet interface
product: Ethernet Connection (2) I219-V
vendor: Intel Corporation
physical id: 1f.6
bus info: pci@0000:00:1f.6
logical name: enp0s31f6
version: 31
serial: 34:97:f6:8e:9c:e2
size: 100Mbit/s
capacity: 1Gbit/s
width: 32 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=3.2.6-k duplex=full firmware=0.8-4 ip=192.168.178.93 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s
resources: irq:127 memory:f7300000-f731ffff
有人能帮我吗？
编辑#1：输出ip a：
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp0s31f6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 34:97:f6:8e:9c:e2 brd ff:ff:ff:ff:ff:ff
inet 192.168.178.93/24 brd 192.168.178.255 scope global dynamic noprefixroute enp0s31f6
valid_lft 805451sec preferred_lft 805451sec
inet6 fe80::5e03:8c96:eeaa:979a/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: wlp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
link/ether 14:da:e9:f1:a6:6d brd ff:ff:ff:ff:ff:ff
inet 192.168.178.94/24 brd 192.168.178.255 scope global dynamic noprefixroute wlp2s0
valid_lft 800956sec preferred_lft 800956sec
inet6 fe80::3ea3:7811:db83:317/64 scope link noprefixroute
valid_lft forever preferred_lft forever
编辑#2：输出ethtool -g enp0s31f6
Ring parameters for enp0s31f6:
Pre-set maximums:
RX: 4096
RX Mini: 0
RX Jumbo: 0
TX: 4096
Current hardware settings:
RX: 256
RX Mini: 0
RX Jumbo: 0
TX: 256
编辑#3：[已删除]
编辑 #4：所以我刚刚运行了 Ubuntu 19.04 Live USB 版本。我在那里也遇到了同样的问题。同样的消息在 中/var/log/kern.log。此外，我在 中收到以下消息kern.log：Driver has suspect GRO implementation, TCP performance may be compromised.
编辑#5：
所以我找到了一个解决方法：我现在使用 USB 以太网适配器（路由器->以太网->适配器->USB->PC）。
更多信息：自从我最初描述问题以来，我认为连接中断发生在我单击链接、打开新选项卡并开始网络搜索时。因此，这可能与启动 http 请求有关。但我不确定。下载大文件时，我不会在下载过程中遇到连接中断的情况。
编辑#6：kern.log禁用 lan 并仅使用 wlan 时：
May 5 18:09:20 i7 kernel: [ 108.077780] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 1 (2462/0 MHz)
May 5 18:09:21 i7 kernel: [ 108.897066] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 2 (2452/0 MHz)
May 5 18:09:22 i7 kernel: [ 109.920896] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 1 (2462/0 MHz)
May 5 18:09:32 i7 kernel: [ 120.161068] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 2 (2452/0 MHz)
May 5 18:09:42 i7 kernel: [ 130.271599] rtlwifi: AP off, try to reconnect now
May 5 18:09:42 i7 kernel: [ 130.271653] wlp2s0: Connection to AP 24:65:11:ad:a3:4a lost
May 5 18:09:43 i7 kernel: [ 131.417327] wlp2s0: authenticate with 24:65:11:ad:a3:4a
May 5 18:09:43 i7 kernel: [ 131.437037] wlp2s0: send auth to 24:65:11:ad:a3:4a (try 1/3)
May 5 18:09:43 i7 kernel: [ 131.440142] wlp2s0: authenticated
May 5 18:09:43 i7 kernel: [ 131.444617] wlp2s0: associate with 24:65:11:ad:a3:4a (try 1/3)
May 5 18:09:43 i7 kernel: [ 131.451848] wlp2s0: RX AssocResp from 24:65:11:ad:a3:4a (capab=0x431 status=0 aid=3)
May 5 18:09:43 i7 kernel: [ 131.452237] wlp2s0: associated
May 5 18:09:46 i7 kernel: [ 133.985199] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 1 (2462/0 MHz)
May 5 18:09:47 i7 kernel: [ 134.906814] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 2 (2452/0 MHz)
May 5 18:10:20 i7 kernel: [ 168.085188] wlp2s0: AP 24:65:11:ad:a3:4a changed bandwidth, new config is 2462 MHz, width 1 (2462/0 MHz)
编辑#7：ethtool -k enp0s31f6
Features for enp0s31f6:
rx-checksumming: on
tx-checksumming: on
tx-checksum-ipv4: off [fixed]
tx-checksum-ip-generic: on
tx-checksum-ipv6: off [fixed]
tx-checksum-fcoe-crc: off [fixed]
tx-checksum-sctp: off [fixed]
scatter-gather: on
tx-scatter-gather: on
tx-scatter-gather-fraglist: off [fixed]
tcp-segmentation-offload: off
tx-tcp-segmentation: off [requested on]
tx-tcp-ecn-segmentation: off [fixed]
tx-tcp-mangleid-segmentation: off
tx-tcp6-segmentation: off [requested on]
udp-fragmentation-offload: off
generic-segmentation-offload: on
generic-receive-offload: on
large-receive-offload: off [fixed]
rx-vlan-offload: on
tx-vlan-offload: on
ntuple-filters: off [fixed]
receive-hashing: on
highdma: on [fixed]
rx-vlan-filter: off [fixed]
vlan-challenged: off [fixed]
tx-lockless: off [fixed]
netns-local: off [fixed]
tx-gso-robust: off [fixed]
tx-fcoe-segmentation: off [fixed]
tx-gre-segmentation: off [fixed]
tx-gre-csum-segmentation: off [fixed]
tx-ipxip4-segmentation: off [fixed]
tx-ipxip6-segmentation: off [fixed]
tx-udp_tnl-segmentation: off [fixed]
tx-udp_tnl-csum-segmentation: off [fixed]
tx-gso-partial: off [fixed]
tx-sctp-segmentation: off [fixed]
tx-esp-segmentation: off [fixed]
tx-udp-segmentation: off [fixed]
fcoe-mtu: off [fixed]
tx-nocache-copy: off
loopback: off [fixed]
rx-fcs: off
rx-all: off
tx-vlan-stag-hw-insert: off [fixed]
rx-vlan-stag-hw-parse: off [fixed]
rx-vlan-stag-filter: off [fixed]
l2-fwd-offload: off [fixed]
hw-tc-offload: off [fixed]
esp-hw-offload: off [fixed]
esp-tx-csum-hw-offload: off [fixed]
rx-udp_tunnel-port-offload: off [fixed]
tls-hw-tx-offload: off [fixed]
rx-gro-hw: off [fixed]
tls-hw-record: off [fixed]
答案1
第一次尝试电源循环拔下路由器的电源插头/等待 10 秒钟/从交流电源重新插入。重新检查掉线问题。
对于以太网掉线问题...虽然这不是首选的解决方案，但您可以尝试一下，看看它是否能解决问题...
在 中terminal，使用nm-connection-editor，将“链路协商”设置为“手动/100Mb/完整”。
答案2
解决方案是在每次启动后运行以下命令（将 INTERFACENAME 替换为以太网接口的实际名称）：
/usr/sbin/ethtool --change INTERFACENAME speed 100 duplex half autoneg off
我使用这个 systemd 服务单元在启动时运行命令：
[Unit]
Description=Ethernet Fix
After=network-online.target
[Service]
ExecStart=PATH_TO_BASH_SCRIPT
[Install]
WantedBy=multi-user.target