Yeah, there are so many moving parts in something like this. But the first 2 key questions are:
Is the OS recognizing the network adapter?
Is the network adapter seeing the router?
If you don't have an "eth0" device, you need to start with the OS finding the hardware. If all that looks OK, but you're getting a bogus IP address, you need to get the thing to find your router/modem so it can get an IP address. If you have a good IP address, you need to look at DNS settings and such.
So many places for things to go awry...