Realtek RTL8168/8111E and Ubuntu Linux
If you are using Ubuntu (and probably other distributions too) and you have an on board Realtek RTL8168/8111E PCI Express network adapter you might find your network not working as it should. Slow connections or no connection at all and your logs full of messages like these:
Oct 02 09:13:25 machine kernel: r8169 0000:04:00.0: eth0: link up Oct 02 12:45:17 machine kernel: r8169 0000:04:00.0: eth0: link up Oct 02 12:45:20 machine kernel: r8169 0000:04:00.0: eth0: link up Oct 02 13:15:12 machine kernel: r8169 0000:04:00.0: eth0: link up Oct 02 13:15:13 machine kernel: r8169 0000:04:00.0: eth0: link up Oct 02 13:22:13 machine kernel: r8169 0000:04:00.0: eth0: link up
Read on if you want to know why this happens and how to solve the problem.