Ubuntu can't connect to the internet, restart required

Question

Today for the 4th time this month,
Ubuntu suddenly disables my Ethernet,
I'm connected through Alcatel Speed Touch (yeah I know it's an oldie).
I tried to log out and log back in, tried ifconfig and it didn't recognized
any Ethernet modem connected.
Only after a reset did it work... like every time before.
Any ideas?

UPDATE
Tried to enter
/etc/init.d/gdm restart
and then after the gui restarted
sudo dhclient eth0

That worekd, but I still want to know what's wrong
and why does it stop working all the time

UPDATE 2
the dhclient eth0 thing doesn't work anymore.
Any ideas?

Answer 1

This is known bug with r8169 ethernet cards. For reference, it is bug #566389 on the Redhat bug tracker or #605045 on the Network-Manager Ubuntu bug tracker.

A current workaround is to place this in /etc/pm/sleep.d/85-network-r8169-module [1]

#!/bin/bash
case $1 in
  hibernate | suspend)
    echo "Removing r8169."
    modprobe -r r8169
    ;;
thaw | resume)
    echo 3 > /proc/sys/vm/drop_caches
    modprobe r8169
    ;;
*)
    ;;
esac
exit 0

However, it will make resuming a bit slower.

[1] https://bugzilla.redhat.com/show_bug.cgi?id=566389#c6