What speed (bits per second) is your home network/router running? It is possible the Vizio can't step down (or up) to it. Common for home networking is 10 million bits per second (Mbps) or 100 Mbps. The Vizio should support those out of the box but...
Does your home router provide DHCP services? (dynamic host control protocol) The Vizio may (probably does) require an active DHCP server to contact to assign it an IP address.
Related to that, maybe the Vizio doesn't require DHCP, maybe it comes pre-configured to a fixed address, and that address is either in conflict with one already in use on your network, or is on the wrong subnet.
Subnets could be a problem. Common ones are 192.168.0.x (where x is a number from 0 to 255) and 192.168.1.x... I've got a couple of routers and of course one defaults to the .0 subnet, one to the .1 - so any time I factory reset one, I have to go find it (in IP land) and reconfigure it. You may have to configure the Vizio to be on the same local subnet as your router.
It could be you're not using DHCP at all, and instead you are simply passing through DHCP requests for an address assignment to your ISP. Your ISP may have a limit on the number of IP addresses it is willing to give each customer, so you could simply be being refused an IP address.
It could be that your Vizio requires an open port to allow connections coming back in from the Internet. Kind of technically dangerous (can allow hackers in onto your lan), but who knows. That would be a manual configuration step on your router to open up a port and pass-through connections to an inside machine. If your router has a "DMZ" (de-militarized zone) port, try using that. Note, you may have to enable DMZ in the router config.
None of these suggestions are networking rocket science, pretty basic stuff any Vizio tech support person should know the answers to. But hey, you never know, hope these help. Mail me if any of these look promising - ie. tech support didn't go down this path - and you want details on any of these. I'm not a networking guy, but I do know a little about it.
No - they didn’t check any of those things. They only ran through three steps which reset the TVs to factory settings.
Let me look around and I will try to get answers to these questions and work on it again tomorrow. Completely fed up with it tonight. I’ve spent so many hours trying to get it to work. It’s definitely not worth the effort.