USB启动系统下以太网无法工作但Wi-Fi正常的故障求助（Windows下以太网正常）

大家好，我碰到一个头疼的网络问题：我用USB启动的Linux系统，Wi-Fi能正常连接上网，但以太网完全没法用。奇怪的是同一台机器在Windows系统下以太网是正常工作的，所以硬件本身应该没问题。

我收集了几个网络命令的输出，希望能帮大家定位问题：

1. nmcli 输出 #

enp7s0: connected to Wired connection 1
"Realtek RTL8111/8168/8411"
ethernet (r8169), F8:75:A4:66:B9:DA, hw, mtu 1500
ip4 default
inet4 192.168.1.10/24
route4 192.168.1.0/24 metric 100
route4 default via 192.168.1.1 metric 100
route4 169.254.0.0/16 metric 1000
inet6 fe80::19f7:d285:68c8:9100/64
route6 fe80::/64 metric 1024

wlp0s20f3: connected to Euphoria
"Intel Cannon Lake PCH CNVi"
wifi (iwlwifi), 60:F2:62:73:CD:8C, hw, mtu 1500
inet4 192.168.1.14/24
route4 192.168.1.0/24 metric 600
route4 default via 192.168.1.1 metric 600
inet6 fdd8:2918:fbc8:a400:2e06:7b82:bf45:9498/64
inet6 fdd8:2918:fbc8:a400:b0c5:ac74:e7cd:c270/64
inet6 fe80::d074:1e18:3146:73a8/64
route6 fe80::/64 metric 1024
route6 fdd8:2918:fbc8:a400::/64 metric 600

lo: connected (externally) to lo
"lo"
loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536
inet4 127.0.0.1/8
inet6 ::1/128
route6 ::1/128 metric 256

p2p-dev-wlp0s20f3: disconnected
"p2p-dev-wlp0s20f3"
wifi-p2p, hw

DNS configuration:
servers: 8.8.8.8
interface: enp7s0
servers: 192.168.1.1
domains: home
interface: wlp0s20f3

2. nmcli device show 输出 #

GENERAL.DEVICE:                         enp7s0
GENERAL.TYPE:                           ethernet
GENERAL.HWADDR:                         F8:75:A4:66:B9:DA
GENERAL.MTU:                            1500
GENERAL.STATE:                          100 (connected)
GENERAL.CONNECTION:                     Wired connection 1
GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/2
WIRED-PROPERTIES.CARRIER:               on
IP4.ADDRESS[1]:                         192.168.1.10/24
IP4.GATEWAY:                            192.168.1.1
IP4.ROUTE[1]:                           dst = 192.168.1.0/24, nh = 0.0.0.0, mt = 100
IP4.ROUTE[2]:                           dst = 0.0.0.0/0, nh = 192.168.1.1, mt = 100
IP4.ROUTE[3]:                           dst = 169.254.0.0/16, nh = 0.0.0.0, mt = 1000
IP4.DNS[1]:                             8.8.8.8
IP6.ADDRESS[1]:                         fe80::19f7:d285:68c8:9100/64
IP6.GATEWAY:                            --
IP6.ROUTE[1]:                           dst = fe80::/64, nh = ::, mt = 1024

GENERAL.DEVICE:                         wlp0s20f3
GENERAL.TYPE:                           wifi
GENERAL.HWADDR:                         60:F2:62:73:CD:8C
GENERAL.MTU:                            1500
GENERAL.STATE:                          100 (connected)
GENERAL.CONNECTION:                     Euphoria
GENERAL.CON-PATH:                       /org/freedesktop/NetworkManager/ActiveConnection/4
IP4.ADDRESS[1]:                         192.168.1.14/24
IP4.GATEWAY:                            192.168.1.1

3. ip a 输出 #

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: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether f8:75:a4:66:b9:da brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.10/24 brd 192.168.1.255 scope global noprefixroute enp7s0
       valid_lft forever preferred_lft forever
    inet6 fe80::19f7:d285:68c8:9100/64 scope link noprefixroute
       valid_lft forever preferred_lft forever
3: wlp0s20f3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 60:f2:62:73:cd:8c brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.14/24 brd 192.168.1.255 scope global dynamic noprefixroute wlp0s20f3
       valid_lft 86067sec preferred_lft 86067sec
    inet6 fdd8:2918:fbc8:a400:2e06:7b82:bf45:9498/64 scope global temporary dynamic
       valid_lft 7142sec preferred_lft 3542sec
    inet6 fdd8:2918:fbc8:a400:b0c5:ac74:e7cd:c270/64 scope global dynamic mngtmpaddr noprefixroute
       valid_lft 7142sec preferred_lft 3542sec
    inet6 fe80::d074:1e18:3146:73a8/64 scope link noprefixroute
       valid_lft forever preferred_lft forever

4. ifconfig 输出 #

enp7s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.10  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::19f7:d285:68c8:9100  prefixlen 64  scopeid 0x20<link>
        ether f8:75:a4:66:b9:da  txqueuelen 1000  (Ethernet)
        RX packets 30  bytes 12167 (12.1 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 49  bytes 7866 (7.8 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

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 1666  bytes 221974 (221.9 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1666  bytes 221974 (221.9 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlp0s20f3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.14  netmask 255.255.255.0  broadcast 192.168.1.255
        inet6 fe80::d074:1e18:3146:73a8  prefixlen 64  scopeid 0x20<link>
        inet6 fdd8:2918:fbc8:a400:b0c5:ac74:e7cd:c270  prefixlen 64  scopeid 0x0<global>
        inet6 fdd8:2918:fbc8:a400:2e06:7b82:bf45:9498  prefixlen 64  scopeid 0x0<global>
        ether 60:f2:62:73:cd:8c  txqueuelen 1000  (Ethernet)
        RX packets 367  bytes 63478 (63.4 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 340  bytes 43790 (43.7 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

5. ping 192.168.1.1 输出 #

PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
From 192.168.1.10 icmp_seq=1 Destination Host Unreachable
From 192.168.1.10 icmp_seq=2 Destination Host Unreachable
From 192.168.1.10 icmp_seq=3 Destination Host Unreachable
From 192.168.1.10 icmp_seq=4 Destination Host Unreachable

--- 192.168.1.1 ping statistics ---
25 packets transmitted, 0 received, +24 errors, 100% packet loss, time 24562ms

6. arp -a 输出 #

? (192.168.1.9) at 9e:d8:ef:e0:d6:98 [ether] on wlp0s20f3
? (192.168.1.1) at d8:29:18:fb:c8:a4 [ether] on wlp0s20f3
? (192.168.1.1) at <incomplete> on enp7s0
? (192.168.1.9) at <incomplete> on enp7s0

我自己观察到，以太网接口enp7s0上没法获取网关192.168.1.1的ARP条目，显示<incomplete>，但Wi-Fi接口上是正常的。而且Windows下以太网没问题，所以肯定不是硬件坏了。

有没有朋友遇到过类似的USB启动系统下以太网驱动或者配置问题？麻烦给点排查思路或者解决办法，谢谢大家！

备注：内容来源于stack exchange，提问作者MeedoW