Plex saying it cannot make a secure connection to my new My Cloud Home 4TB

I bought a My Cloud Home 4TB at the weekend and have spent the last 5 days backing all my music up to it from various other drives, I have all the files and folders in the Plex folder and the service enabled. I have used the android app to login to my Plex account and “claimed” the My Cloud Home. But now that I’ve done all this, Plex is showing an error that it can’t make a secure connection to the My Cloud Home. This is happening on all my devices, android and Windows.

Any help to resolve this would be appreciated, as we’re having a family get together this evening and I want to have a playlist ready before everyone starts arriving.