Hisense - Plex server currently unavailable

***Update

So without doing anything apart from rebooting my TerraMaster, turning Hisense TV off by the plug and my internet router all off, it is now working on my Hisense TV.

However, it will not direct play so everything is coming through as SD quality. On my phone/tablet/Roku device, direct stream works and plays all files as normal.

Anyone recommend how to get direct play working on Hisense? I have done the settings to force direct play but on the playback information it says it was not able to do so.

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Recently, Plex all of a sudden would not work on my Hisense TV. It would work on all other devices, laptop, android or apple phones, Roku devices too and had previously worked in Hi sense with no problems at all.

Currently the error message I get is that the server is unavailable on Hisense.

I needed to upgrade my TerraMaster NAS from TOS5 to TOS6 anyway so took this opportunity to refresh the whole system……..however, on reinstall and setup, Plex still shows the same message with all the default settings.

I did see about allowing unsecure network connections, but I have tried that and tried changing multiple settings on the Plex TV app and ok Plex on the NAS server with no success.

Any recommendations would be hugely appreciated.