2018 LG - can not find server



My uncle just bought a 2018 LG tv and I was trying to connect to my plex server. I used the login from the menu and kept getting a screen that said it couldn’t find my server. I thought my server was down, so I tried on my iPhone and it was fine. I was even using his internet connection.
I could see my account logged in at the top corner, but as many times as I would hit rettry it wouldn’t find the server.
The tv is connected to an Apple airport server for dhcp and WiFi and then into the router.
Anyone have any ideas?
I read some stuff about adding ip addresses, but that sounded like old information based on older lg TVs.