I have an Acer Travelmate C110 with Ubuntu 11.10. There's a built in network card, when I connect the cable to it everything works fine (mail, internet,...). I now bought a USB ethernet adapter. (It works perfect with Win7 (had to install a driver)). For ubuntu: Ubuntu installed the driver for it (dm9601) - i can check it with lsmod. I also have a eth1 when I check with ifconfig. There are two 'wired connections' in the network Connections dialog box. 'Wired connection 2' is the eth1. All settings are the same for both connections in this dialog box.
So everything seems ok yet no internet. When I check through System Settings>Network, I have 2 wired symbols both say 'Cable unplugged'. Yet when i put the cable in the built in network card of the laptop: internet works. If I switch the cable to the USB ethernet adapter, ubuntu remains telling the cable is unplugged for that adapter - even if its the same cable. If I switch the cable with adapter to Win7: everything works.
To conclude: - I see no obvious hardware problem - driver dm9601 installed - a second connection show up on differents places (ifconfig, network dialog box, network connections dialog box): so that seems to be ok also. - network dialog box says: 'Cable unplugged' while its plugged in
thanks for any suggestions!