I already looked for other questions maybe answering this, but nothing really seems to apply here. After a fresh install of 12.04, I can't get a wired connection established. WLAN works fine. What really surprises me is that my router interface shows that I am connected over LAN.
So how do I find out whats wrong here?
Don't know where to look further, but here is some relevant inforamation.
(To be exact regarding the history of this: I had a working installation of 12.04 before, then I got problems with the networking a day ago, and there was WLAN and LAN affected. After some attempts to fix this, I decided to do a fresh install. But now I am stuck in this situation, which is basically better because now I am at least able to connect over wifi.)
$ ifconfig
eth0 Link encap:Ethernet Hardware Adresse 20:cf:30:67:3f:5f
inet6-Adresse: fe80::22cf:30ff:fe67:3f5f/64 Gültigkeitsbereich:Verbindung
UP BROADCAST RUNNING MULTICAST MTU:1500 Metrik:1
RX-Pakete:0 Fehler:0 Verloren:0 Überläufe:0 Fenster:0
TX-Pakete:791 Fehler:0 Verloren:0 Überläufe:0 Träger:1
Kollisionen:0 Sendewarteschlangenlänge:1000
RX-Bytes:0 (0.0 B) TX-Bytes:163547 (163.5 KB)
$ nmcli dev list iface eth0
GENERAL.GERÄT: eth0
GENERAL.TYP: 802-3-ethernet
GENERAL.HERSTELLER: Atheros Communications Inc.
GENERAL.PRODUKT: AR8131 Gigabit Ethernet
GENERAL.TREIBER: atl1c
GENERAL.HWADDR: 20:CF:30:67:3F:5F
GENERAL.STATUS: 30 (nicht verbunden)
GENERAL.GRUND: 0 (Kein Grund angegeben)
GENERAL.UDI: /sys/devices/pci0000:00/0000:00:1c.5/0000:05:00.0/net/eth0
GENERAL.IP-IFACE:
GENERAL.NM-VERWALTET: ja
GENERAL.FIRMWARE-FEHLT: nein
GENERAL.VERBINDUNG: nicht verbunden
CAPABILITIES.TRÄGERFREQUENZERKENNUNG: ja
CAPABILITIES.GESCHWINDIGKEIT: 100 Mb/s
WIRED-PROPERTIES.TRÄGERFREQUENZ: an