I am brand new to Ubuntu and Ubuntu Server. My aim is to set up a Plex media server using Ubuntu Server 16.04 LTS. Ubuntu has been successfully installed on my system which has a hard wired internet connection but I keep getting errors and "Failed to fetch..." prompts after executing command "sudo apt-get update". Even after restarting the system and/or powering off and restarting, the issue remains.
I also tried to ping Google.com using "ping -c3 www.google.com" but I get the response "unknown host www.google.com" so not sure if there might be a network issue (see attached image for errors and other issues mentioned).
[Image showing command line errors]
I've done quite a bit of scouring but can't seem to find a solution. I am also new to the CLI, so any help would be much appreciated.
I had initially set up my server with a static IP but was getting no internet connection. As per instruction from @Joel to get a new IP address from my router, a new IP was obtained by updating the Network Interfaces file using the VI Editor (command: sudo vi /etc/network/interfaces) and changing the primary network interface back to 'dhcp' from 'static' (iface enp3s0 inet dhcp).
After rebooting I was successfully able to ping 126.96.36.199 (Google) and thus perform updates.
Big thanks to @joel and @f35 for your support.