I just updated my laptop from 17.10 to 18.04 LTS. However, only my wifi connection still works, while the lan connection is not able to work anymore.
I saw that others ran into similar issues after updating their system, however, nothing worked for me. Maybe someone has an idea. 
ifconfig gives me this output:

```
~$ ifconfig 
   enp0s31f6: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    ether 54:e1:ad:bb:4d:5f  txqueuelen 1000  (Ethernet)
    RX packets 32507  bytes 5736300 (5.7 MB)
    RX errors 0  dropped 327  overruns 0  frame 0
    TX packets 1687  bytes 1327985 (1.3 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    device interrupt 16  memory 0xf1300000-f1320000  

   lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
    inet 127.0.0.1  netmask 255.0.0.0
    inet6 ::1  prefixlen 128  scopeid 0x10<host>
    loop  txqueuelen 1000  (Lokale Schleife)
    RX packets 2599  bytes 221934 (221.9 KB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 2599  bytes 221934 (221.9 KB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

   wlp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
    inet 134.93.216.46  netmask 255.255.240.0  broadcast 134.93.223.255
    inet6 fe80::3e0f:9ef1:2208:6a3e  prefixlen 64  scopeid 0x20<link>
    inet6 2001:4c80:40:539:4dc9:e32f:747b:7f6a  prefixlen 64  scopeid 0x0<global>
    inet6 2001:4c80:40:539:f6b2:e234:8e22:6e62  prefixlen 64  scopeid 0x0<global>
    ether 00:28:f8:55:06:b8  txqueuelen 1000  (Ethernet)
    RX packets 682246  bytes 1011624146 (1.0 GB)
    RX errors 0  dropped 0  overruns 0  frame 0
    TX packets 111926  bytes 13380382 (13.3 MB)
    TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

```

My `/etc/network/interfaces` looks like this:

```
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback

```

Any help is appreciated.
Thanks, Daniel