If you look at the server log, all requests to the vuplus server are timing out. Are you sure it is configured correctly?
Bit of a saga, but it appears that Emby Theater Desktop is now working with the Vu+ plugin, and invoking the external player PotPlayer 64 bit.
1. Repeated attempts to connect to the Vu+ server appeared to have locked it up and it needed to be rebooted.
2. I was eventually able to get Live TV to work with the Next PVR and then Vu+ plugins, with no external player configured.
3. It appears that the Vu+ plugin still needed the Hauppauge USB tuner to be added as a TV source for Live TV to work.
4. I then tried the NextPVR plugin again and found that it was no longer working, with or without an external player configured. No idea why.
5. However I then found that the Vu+ plugin configured with the Hauppauge USB tuner was working with PotPlayer 64 bit configured as an external player in Emby Desktop. Moreover the Live TV stream was playing in the external player, looked to be able to capable of timeshifting, and was displaying teletext as subtitles. All of this is good news, as long as the setup is stable.
Having Live TV working in Emby Desktop with an external player configured is much appreciated, but I still don't know why the NextPVR plugin stopped working. Perhaps swapping backwards and forwards with the Vu+ plugin, and between internal and eternal players in Emby Desktop, was difficult for either Emby Server or Desktop to accommodate. I would also have preferred to have Live TV work from with the PVR's internal tuners when using the Vu+ plugin, rather than the Hauppauge USB tuner which has a relatively weak RF signal. It appears that the Vu+ plugin cannot work without the Hauppauge USB tuner.
Just as an aside, something consumed all free space (127 GB) on my system disk SSD overnight, but was cleared on logoff/logon. I wondered if it might be Emby Server log files at AppData\Roaming\Emby-Server\programdata. Most log files there are less than a megabyte, but I have two extra large files there from this morning at 178 MB and 748 MB.