最近更新后，Ubuntu 不断连接，然后断开以太网连接。有什么想法吗？我尝试切换电缆和插头以确保这不是硬件问题。我还执行了“sudo apt-get install r8168-dkms”来重新安装驱动程序。我在网上找到的一些部分解决方案建议检查“/etc/network/interfaces”，这就是我得到的结果：
# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback
就这些，与那些解决方案相比，这看起来相当不对劲，但我完全不知道该如何修复它。我在使用 DELL XPS 13 9380。谢谢帮助！！
更新：
根据@tai271828的回复，以下是 lspci -nn 的输出（是的，我正在使用加密狗。谢谢！）：
00:00.0 Host bridge [0600]: Intel Corporation Device [8086:3e34] (rev 0b)
00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:3ea0]
00:04.0 Signal processing controller [1180]: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem [8086:1903] (rev 0b)
00:08.0 System peripheral [0880]: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th Gen Core Processor Gaussian Mixture Model [8086:1911]
00:12.0 Signal processing controller [1180]: Intel Corporation Device [8086:9df9] (rev 30)
00:14.0 USB controller [0c03]: Intel Corporation Device [8086:9ded] (rev 30)
00:14.2 RAM memory [0500]: Intel Corporation Device [8086:9def] (rev 30)
00:15.0 Serial bus controller [0c80]: Intel Corporation Device [8086:9de8] (rev 30)
00:15.1 Serial bus controller [0c80]: Intel Corporation Device [8086:9de9] (rev 30)
00:16.0 Communication controller [0780]: Intel Corporation Device [8086:9de0] (rev 30)
00:1c.0 PCI bridge [0604]: Intel Corporation Device [8086:9dbc] (rev f0)
00:1c.6 PCI bridge [0604]: Intel Corporation Device [8086:9dbe] (rev f0)
00:1d.0 PCI bridge [0604]: Intel Corporation Device [8086:9db0] (rev f0)
00:1d.4 PCI bridge [0604]: Intel Corporation Device [8086:9db4] (rev f0)
00:1f.0 ISA bridge [0601]: Intel Corporation Device [8086:9d84] (rev 30)
00:1f.3 Audio device [0403]: Intel Corporation Device [8086:9dc8] (rev 30)
00:1f.4 SMBus [0c05]: Intel Corporation Device [8086:9da3] (rev 30)
00:1f.5 Serial bus controller [0c80]: Intel Corporation Device [8086:9da4] (rev 30)
01:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. RTS525A PCI Express Card Reader [10ec:525a] (rev 01)
02:00.0 Network controller [0280]: Qualcomm Atheros QCA6174 802.11ac Wireless Network Adapter [168c:003e] (rev 32)
03:00.0 PCI bridge [0604]: Intel Corporation JHL6540 Thunderbolt 3 Bridge (C step) [Alpine Ridge 4C 2016] [8086:15d3] (rev 02)
04:00.0 PCI bridge [0604]: Intel Corporation JHL6540 Thunderbolt 3 Bridge (C step) [Alpine Ridge 4C 2016] [8086:15d3] (rev 02)
04:01.0 PCI bridge [0604]: Intel Corporation JHL6540 Thunderbolt 3 Bridge (C step) [Alpine Ridge 4C 2016] [8086:15d3] (rev 02)
04:02.0 PCI bridge [0604]: Intel Corporation JHL6540 Thunderbolt 3 Bridge (C step) [Alpine Ridge 4C 2016] [8086:15d3] (rev 02)
04:04.0 PCI bridge [0604]: Intel Corporation JHL6540 Thunderbolt 3 Bridge (C step) [Alpine Ridge 4C 2016] [8086:15d3] (rev 02)
05:00.0 System peripheral [0880]: Intel Corporation JHL6540 Thunderbolt 3 NHI (C step) [Alpine Ridge 4C 2016] [8086:15d2] (rev 02)
39:00.0 USB controller [0c03]: Intel Corporation JHL6540 Thunderbolt 3 USB Controller (C step) [Alpine Ridge 4C 2016] [8086:15d4] (rev 02)
6e:00.0 Non-Volatile memory controller [0108]: SK hynix Device [1c5c:1527]
更新：
我换了其他以太网转 USB-C 适配器，它们都工作正常。唯一一个在这次更新后无法正常工作的是戴尔 DA300，它才 4 个月大，一直放在我的桌子上。我还尝试将以太网电缆插入 USB-C 适配器，然后将该适配器插入 DA300，结果成功了。很难相信这只是由于硬件损坏造成的，因为插入以太网电缆时它总是可以检测到连接，但无法建立连接，但我无法排除这种可能性。
更新：
来自 journalctl /usr/sbin/NetworkManager，显示立即连接/断开连接，原因我不理解
<info> [1564007509.2735] device (enxc8f7509d89c6): carrier: link connected
<info> [1564007509.2740] device (enxc8f7509d89c6): state change: unavailable -> disconnected (reason 'carrier-changed', sys-iface-state: 'managed')
<info> [1564007510.2992] device (enxc8f7509d89c6): state change: disconnected -> unavailable (reason 'carrier-changed', sys-iface-state: 'managed')