"Unable to fetch auth providers" from remote Nabu Casa connection

Hi

As I will be away from my house for a while I decided to go for a Nabu Casa subscription so I could keep a remote eye on my Home Assistant running on a discrete Intel NUC.

This worked well for around two weeks and then :-

Unable to fetch auth providers. https://my address.ui.nabu.casa/?auth_callback=1 from Chrome

and other unable to connect messages from Safari and Microsoft Edge.

How do I resolve this ?

Regards