我有一个连接到 Lenovo P50 的 Dell D6000 USB-C 坞站。 USB 以太网接口启动后仅工作几秒钟，然后停止工作。例如，如果我对我的路由/网关运行 ping，它会显示“主机无法访问”。如果我关闭接口并重新打开它，我会在它变得无法访问之前看到一些成功的 ping。当我物理拔下并重新插入以太网电缆时，也会发生同样的情况：
$ ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
ping: sendmsg: Network is unreachable
From 192.168.1.124 icmp_seq=10 Destination Host Unreachable # this is where I unplug the cable
From 192.168.1.124 icmp_seq=11 Destination Host Unreachable
From 192.168.1.124 icmp_seq=12 Destination Host Unreachable # plugged the cable back in a waited a second...
64 bytes from 192.168.1.1: icmp_seq=13 ttl=64 time=1859 ms
64 bytes from 192.168.1.1: icmp_seq=14 ttl=64 time=842 ms
64 bytes from 192.168.1.1: icmp_seq=15 ttl=64 time=1.72 ms
64 bytes from 192.168.1.1: icmp_seq=16 ttl=64 time=2.05 ms
64 bytes from 192.168.1.1: icmp_seq=17 ttl=64 time=1.81 ms
ethtool 没有显示太多界面：
$ sudo ethtool enp0s20f0u2u1i5
Settings for enp0s20f0u2u1i5:
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes
同样的问题也开始出现在 Linux Mint cinnamon 中。我切换到 Pop!_OS 并遇到了同样的问题。尝试过Manjaro KDE，同样的问题。费多拉，同样的问题。所以我在多个发行版和内核中都遇到了同样的问题。它确实可以工作的最后一个发行版是 KDE Neon，我相信我也可以在 Fedora KDE 上使用它。我还可以确认它可以在 Windows 上运行。我现在使用的是 Fedora 32 (Gnome)，但仍然遇到同样的问题。下面是一些命令的输出，可能会提供一些有用的见解
$ dmesg | grep enp0s20f0u2u1i5
[ 4.035631] cdc_ncm 2-2.1:1.5 enp0s20f0u2u1i5: renamed from usb0
[ 12.812439] cdc_ncm 2-2.1:1.5 enp0s20f0u2u1i5: network connection: disconnected
[ 12.844436] cdc_ncm 2-2.1:1.5 enp0s20f0u2u1i5: network connection: connected
[ 13.002757] IPv6: ADDRCONF(NETDEV_CHANGE): enp0s20f0u2u1i5: link becomes ready
[ 75.212542] cdc_ncm 2-2.1:1.5 enp0s20f0u2u1i5: network connection: disconnected
[ 81.436679] cdc_ncm 2-2.1:1.5 enp0s20f0u2u1i5: 1000 mbit/s downlink 1000 mbit/s uplink
[ 81.468677] cdc_ncm 2-2.1:1.5 enp0s20f0u2u1i5: network connection: connected
$ 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: enp0s20f0u2u1i5: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
link/ether 0c:37:96:0d:c2:43 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.124/24 brd 192.168.1.255 scope global dynamic noprefixroute enp0s20f0u2u1i5
valid_lft 604676sec preferred_lft 604676sec
inet6 fe80::5760:8b51:4810:e509/64 scope link noprefixroute
valid_lft forever preferred_lft forever
3: enp0s31f6: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc fq_codel state DOWN group default qlen 1000
link/ether c8:5b:76:2f:cf:8d brd ff:ff:ff:ff:ff:ff
4: wlp4s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether 46:b7:f7:5d:22:1f brd ff:ff:ff:ff:ff:ff
$ modinfo cdc_ncm
filename: /lib/modules/5.6.6-300.fc32.x86_64/kernel/drivers/net/usb/cdc_ncm.ko.xz
license: Dual BSD/GPL
description: USB CDC NCM host driver
author: Hans Petter Selasky
alias: usb:v*p*d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v1546p1010d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v1519p0443d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v12D1p*d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v0930p*d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v413Cp*d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v413Cp81BCd*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v413Cp81BBd*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v1BC7p0036d*dc*dsc*dp*ic02isc0Dip00in*
alias: usb:v0BDBp*d*dc*dsc*dp*ic02isc0Dip00in*
depends: usbnet
retpoline: Y
intree: Y
name: cdc_ncm
vermagic: 5.6.6-300.fc32.x86_64 SMP mod_unload
sig_id: PKCS#7
signer: Fedora kernel signing key
sig_key: 7E:E3:7B:CE:53:8B:CA:A7:B5:4A:A8:CD:5E:E3:4C:2A:A7:52:9A:7A
sig_hashalgo: sha256
signature: 7B:E0:1C:53:E0:A1:BC:75:97:0C:53:0C:E3:A2:BE:52:A3:02:D9:0B:
98:56:AB:96:79:D0:1F:C8:4A:8E:E8:A0:89:18:F3:DD:66:3A:9F:F2:
09:80:EC:C3:BE:96:62:6E:BB:AE:1B:41:AC:FE:F6:19:91:7A:2E:FB:
13:C8:2C:5D:25:EF:71:9C:3B:A6:D1:24:CF:8F:35:C7:DF:53:49:30:
24:24:D7:C3:2C:4C:CA:F2:CF:CE:7B:1F:21:2E:F3:D9:C8:6F:94:FA:
65:B9:25:4D:1B:46:EE:75:1D:FF:CB:E4:C9:50:99:5F:56:CE:83:B1:
E1:E9:87:ED:79:6D:2A:33:4A:FF:88:A3:AE:B7:0E:D5:44:A2:94:50:
2B:1F:85:78:AA:B2:65:D4:28:42:0D:1D:D9:66:05:6B:10:A7:EF:FA:
51:62:18:B9:BE:02:80:55:E1:80:21:43:22:F3:82:4A:C5:66:A1:23:
EF:A0:0D:B6:DF:FE:19:E8:5E:BF:0D:34:A7:36:6B:69:93:7E:C4:42:
04:D0:1C:47:78:94:1A:7D:45:2E:0C:04:7C:CD:81:00:E0:97:30:06:
79:E5:04:9A:25:AD:01:87:6A:BE:06:9E:0B:C4:B9:9A:A6:06:48:CB:
BC:A8:4C:60:E4:DC:5D:2C:C7:4E:19:9E:88:BD:63:AB:42:AC:7E:FF:
BF:5D:4E:4F:9B:2C:B0:15:13:1D:4E:1D:96:EC:EC:8F:50:57:5C:8E:
89:A7:32:7D:B4:3A:63:15:FB:45:D5:29:9C:AE:67:E2:6D:B4:66:28:
7C:C8:70:8A:2F:65:91:D3:F4:0C:70:A3:2B:E1:60:9A:14:2E:BD:59:
E4:C4:3A:10:E6:75:6E:DF:1D:92:4E:DC:EA:5E:27:F4:02:9C:1A:B9:
86:E7:C7:BF:80:D7:48:4E:33:A9:AC:EF:B7:E1:19:28:49:23:7D:EF:
23:D9:F5:E6:79:ED:02:86:1B:BE:06:9B:C2:81:A0:7D:39:71:9F:99:
BC:71:9F:63:AA:59:B0:BC:28:0C:AB:C2:B7:43:F0:8E:B3:89:99:E1:
B5:E1:F1:AE:EC:47:32:F5:64:D1:AF:61:04:BB:9C:A2:FA:6D:64:87:
BA:A2:52:FA:79:1D:A1:A6:C2:37:D5:FE:23:BE:97:22:D2:B6:B6:8F:
45:4C:F2:C6:10:BF:6D:F7:37:3B:25:ED:2C:12:3C:A3:FA:00:DB:C5:
FB:87:19:01:6C:04:CD:4B:29:11:2E:7D:7A:0E:C1:AE:D0:3C:05:ED:
F4:10:EF:00:B1:D8:BB:ED:6F:36:11:A5:1A:AE:AA:98:D3:D9:49:E7:
81:4B:D8:23:B3:99:77:82:CD:58:3D:1F
parm: prefer_mbim:Prefer MBIM setting on dual NCM/MBIM functions (bool)
$ sudo lshw -class network
*-network DISABLED
description: Wireless interface
product: Wireless 8260
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:04:00.0
logical name: wlp4s0
version: 3a
serial: 02:50:6a:2a:d1:22
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=iwlwifi driverversion=5.6.6-300.fc32.x86_64 firmware=36.77d01142.0 8000C-36.ucode latency=0 link=no multicast=yes wireless=IEEE 802.11
resources: irq:135 memory:c4c00000-c4c01fff
*-network
description: Ethernet interface
product: Ethernet Connection (2) I219-LM
vendor: Intel Corporation
physical id: 1f.6
bus info: pci@0000:00:1f.6
logical name: enp0s31f6
version: 31
serial: c8:5b:76:2f:cf:8d
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 firmware=0.8-3 latency=0 link=no multicast=yes port=twisted pair
resources: irq:130 memory:c5700000-c571ffff
*-network
description: Ethernet interface
physical id: 2
bus info: usb@2:2.1
logical name: enp0s20f0u2u1i5
serial: 0c:37:96:0d:c2:43
capabilities: ethernet physical
configuration: broadcast=yes driver=cdc_ncm driverversion=22-Aug-2005 firmware=CDC NCM ip=192.168.1.124 link=yes multicast=yes
$ neofetch
/:-------------:\ [email protected]
:-------------------:: -----------------------
:-----------/shhOHbmp---:\ OS: Fedora 32 (Workstation Edition) x86_64
/-----------omMMMNNNMMD ---: Host: 20EQS2VS00 ThinkPad P50
:-----------sMMMMNMNMP. ---: Kernel: 5.6.6-300.fc32.x86_64
:-----------:MMMdP------- ---\ Uptime: 30 mins
,------------:MMMd-------- ---: Packages: 1684 (rpm)
:------------:MMMd------- .---: Shell: bash 5.0.11
:---- oNMMMMMMMMMNho .----: Resolution: 1920x1080
:-- .+shhhMMMmhhy++ .------/ DE: GNOME 3.36.1
:- -------:MMMd--------------: WM: Mutter
:- --------/MMMd-------------; WM Theme: Adwaita
:- ------/hMMMy------------: Theme: Adwaita [GTK2/3]
:-- :dMNdhhdNMMNo------------; Icons: Adwaita [GTK2/3]
:---:sdNMMMMNds:------------: Terminal: gnome-terminal
:------:://:-------------:: CPU: Intel i7-6820HQ (8) @ 3.600GHz
:---------------------:// GPU: NVIDIA Quadro M2000M
GPU: Intel HD Graphics 530
Memory: 2209MiB / 15841MiB