Plex cannot connect to server

PS3 -> Cable modem -> 2nd router -> PC

I am signed in on both PS3 and PC Plex server. When I run Plex on the PS3 it tells me I am signed in and that it tried to connect to my PC, giving the correct IP address. But it won’t connect to the server.

I turn off the VPN. I restart Plex server. I restart PS3 app. Nothing works. It worked once, last week, after I turned off the VPN. Now it just doesn’t work no matter what I do. I have downloaded tons of metadata for hundreds of files and been able to watch exactly one file once.

So obviously my question is: how do I uninstall this piece of crap from my computer?