Emby randomly unable to reach server

[PX_54 0]

I spent the weekend setting up emby on my WD My Cloud EX2 Ultra, it was all working (other a slight network hiccup in the middle of setup) and I shared it with a friend who had it working also.

I was talking about it today with someone else, and when I've tried to access it I'm getting Unable To Reach Server messages constantly - I've not changed any settings.

I'm able to access my server directly through the WD MyCloud site, and I can also access it via Plex, but for some reason emby can't connect.

I vaguely remember having this issue when I've previously tried to set up emby; that it would be quite temperamental and randomly say it can't connect to the server, when there's no reason it shouldn't.  The hiccup at the weekend, was that it did it in the middle of me trying to set everything up again - though I'm not sure if I actually had an actual network at that point (because some other things seem to point to that possibility). I can't even remember how I rectified it at the weekend, because the webpage just kept saying that it couldn't connect and then I clicked through somewhere which opened a new tab that could connect - but the old tab still couldn't.

This happens both locally and remotely.

I really want to switch to emby, particularly for it's free remote access, but this random loss of access keeps putting me off.