TCL Roku TV can't connect, while Roku stick can
We have a TCL TV (with Roku remote and Plex installed) that a week ago was able to connect to my Plex Media Server on my mac on the local network. This hasn't worked in the past week for no obvious reason, with the error that it was unable to connect to the server. We have a Roku stick that has continued to be able to connect to my Plex server on a different TV, so the server appears to be running and capable of receiving connections. Things we have tried:
-- update PM server on the computer
-- restart the computer
-- update the TCL TV
-- remove and reinstall the app on the TCL TV
-- remove all devices from the PM server device list and re-link the devices
In every case, the Roku stick works fine, while the TCL TV does not. To make sure the TV was the problem, we also plugged the Roku stick into the Roku-enabled TCL TV, and are able to watch movies via the stick but not via the app on the TV.
I'm fairly confident at this point the TCL is the problem, not the server. How can I resolve this issue?