Make sure your unit really is an r8169, and not an r8168. Whilst (as I understand it) the r8169 module is supposed to work with an r8168, at least on my laptop (Acer Aspire E17 (E5-722-425Q), currently 18.04 (up-to-date)), using the r8169 module has resulted in "flakely" behaviour for as long as I can remember, including becoming unusable after a (some?) warm reboot. (Sorry, I cannot recall any specific details, albeit I vaguely recall that was not the only problem I had.) Using the r8168 dkms module, there has not been any(?) problems. However, I believe the r8168 module (in package `r8168-dkms') is specific to r8168 hardware and will not work with an r8169 unit.
Using `lspci' my r8168 is listed as: Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller (rev 12) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1841040 Title: r8169 ethernet sometimes doesn't work after cold boot/boot To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1841040/+subscriptions -- ubuntu-bugs mailing list email@example.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs