True NAS not connecting to network

[Desert_Lightning]

I have a TrueNAS build, it's a used R720. Suddenly I am unable to get it to connect to my network. Even the network switch that it's connected to it shows it's not receiving or transmitting any data. Not sure why. I was just using it for a Plex server and now it's completely inaccessable from the network. It boots and shows connection through the ethernet port until the OS loads up and til the point to where it starts then it stops. No connection whatsoever. It was working before and without warning stopped. I've gone through every forum and can't find a similar instance. I really need help...

 

[JohnDigital]

So from the terminal choose 9 for a shell prompt and type ifconfig and press enter. Post the output here.

It boots and shows connection through the ethernet port until the OS loads up and til the point to where it starts then it stops. No connection whatsoever.

Youll need to elaborate a little further. What starts? What stops?