Guide To Setting Up Mumble On Raspberry Pi  

sorry my bad found the solution: for some reason my pi didnt want to get ip from dhcp so had to assign it manually:
commands with example vallues
cd /etc/network
sudo nano interfaces

auto lo

iface lo inet loopback
iface eth0 inet static
addres 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.1

and
sudo nano /etc/resolv.conf
nameserver 192.168.1.1