我对此进行了很多搜索，但尚未找到解决方案！以下是一些相关的命令输出：
$ ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
ether e0:db:55:ba:d8:2f txqueuelen 1000 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 196 bytes 39618 (39.6 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 3635 bytes 379737 (379.7 KB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 3635 bytes 379737 (379.7 KB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.1.5 netmask 255.255.255.0 broadcast 192.168.1.255
inet6 fe80::d24c:daf:8b52:1424 prefixlen 64 scopeid 0x20<link>
ether 0c:8b:fd:f2:d8:cf txqueuelen 1000 (Ethernet)
RX packets 13068 bytes 7854493 (7.8 MB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 12937 bytes 1966814 (1.9 MB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
$
如您所见，没有 inet 地址（我根据某处的建议禁用了 IPV6。以前，我有时会得到一个 inet6 地址）。但是，可以检测到链接。以下是 ethtool 的输出：
$ sudo ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Half 1000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
1000baseT/Full
Advertised pause frame use: Symmetric Receive-only
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Link partner advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Link partner advertised pause frame use: Symmetric
Link partner advertised auto-negotiation: Yes
Link partner advertised FEC modes: Not reported
Speed: 100Mb/s
Duplex: Full
Port: MII
PHYAD: 0
Transceiver: internal
Auto-negotiation: on
Supports Wake-on: pumbg
Wake-on: d
Current message level: 0x00000033 (51)
drv probe ifdown ifup
Link detected: yes
$
以下是硬件信息：
$ sudo lshw -C network
*-network
description: Wireless interface
product: Wireless 7260
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:02:00.0
logical name: wlan0
version: 73
serial: 0c:8b:fd:f2:d8:cf
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless
configuration: broadcast=yes driver=iwlwifi driverversion=4.15.0-30-generic firmware=17.948900127.0 ip=192.168.1.5 latency=0 link=yes multicast=yes wireless=IEEE 802.11
resources: irq:48 memory:e3500000-e3501fff
*-network
description: Ethernet interface
product: RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0.1
bus info: pci@0000:03:00.1
logical name: eth0
version: 12
serial: e0:db:55:ba:d8:2f
size: 100Mbit/s
capacity: 1Gbit/s
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation
configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8411-2_0.0.1 07/08/13 latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
resources: irq:19 ioport:4000(size=256) memory:e3404000-e3404fff memory:e3400000-e3403fff
$
我看到驱动程序 r8169 已加载（而不是 r8168，因为许多其他人遇到此卡问题），但我没有看到其软件包已安装。不确定这是否是预期的。我应该尝试安装它吗？我没有尝试，因为我不想进一步破坏它。
$ lsmod | grep r8
r8169 86016 0
mii 16384 1 r8169
$ dpkg -l | grep r8
$
我尝试使用以下方法将 eth0 添加到 /etc/networking/interfaces
auto eth0
iface eth0 inet dhcp
然后 sudo ifdown eth0 ; sudo ifup eth0 但是我没有获取 IP 地址。长时间只获取“DHCPDISCOVER”行：
$ sudo ifup eth0
Internet Systems Consortium DHCP Client 4.3.5
Copyright 2004-2016 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/eth0/e0:db:55:ba:d8:2f
Sending on LPF/eth0/e0:db:55:ba:d8:2f
Sending on Socket/fallback
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 21 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 18 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 17 (xid=0xc4c52e42)
DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 18 (xid=0xc4c52e42)
我正在使用带有 Windows 10 的双启动 PC。但是，我有一段时间没有启动 Windows 10 了，上次启动 Windows 10 后，路由器和笔记本电脑都重启了好几次。
一切都运行良好，直到上周我从 16.04 LTS 升级到 18.04.1 LTS。任何帮助都非常感谢。
答案1
好的。问题解决了。以下是我对以太网连接的操作：
在文件 /etc/NetworkManager/NetworkManager.conf 中，我进行了以下更改
[ifupdown]
managed=false
到
[ifupdown]
managed=true
在此之后，我执行了
sudo service NetworkManager restart
以太网开始自动工作！
对于 wifi，我的 NetworkManager 似乎认为它被硬件禁用了（工作了几个小时后）。我使用的是 Dell Inspiron 7537，没有任何硬件开关。我尝试使用 rfkill 来查看它是否是软阻止：
$ rfkill list all
0: dell-rbtn: Wireless LAN
Soft blocked: no
Hard blocked: no
3: phy0: Wireless LAN
Soft blocked: no
Hard blocked: yes
我发现我的键盘上有一个“飞行模式”按钮。按下它后，wifi 开始工作！不过我不确定为什么它被注册为硬阻止而不是软阻止。此后的 rfkill 输出：
$ rfkill list all
0: dell-rbtn: Wireless LAN
Soft blocked: no
Hard blocked: no
3: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
5: hci0: Bluetooth
Soft blocked: no
Hard blocked: no
显然，我的蓝牙之前也被禁用了！