Remote access suddenly stopped working

Server Version#:1.43.0.10492
Player Version#:1.112.0.359-0d79a49f

I watch Plex on my Smart TV app (running Vivo) regularly, and it was working fine last night. Today when I tried to use it it came up with a message saying that in order to watch remotely, I needed a remote watch pass., which I have. This TV is on the same network as my computer which I use as my content storage, and I have watched ‘remotely’ this way even before I had a remote watch pass. Oddly, I can watch on my iPhone, connected to the same network with no issues.

Having opened the Plex app on the computer, I can see that remote access is on, but is showing as ‘not available outside your network’. I have watched outside my network many times on various devices with no issues. Although I now can’t access when not on the network.

I haven’t changed any settings, or made any alterations to my setup in the 12 hours since I last watched on the TV.

I’ve restarted all devices, and the router. Disabled and re-enabled remote access on the Plex server with port forwarding - the same settings as previously. I do have a VPN but this has been running consistently for the past few months, and I even tried disabling the VPN to see if that might be the issue with Plex - it still didn’t work.

I’m not particularly technical, so I’d be grateful if you would bear that in mind when responding.