RBR40 - Circle stopped working

So a few things are now an issue. Firstly, I have an RBR40 - when I go to support pages, I don't see that model listed at all.  Why?  This support form I'm using to post this very question asks for a model number and RBR40 is also not listed in the options I must choose from.  

Secondly, I had Circle working fine for about 8 months and noticed today that it's no longer working.  It's enabled on the router, but the app is wanting to enable it, as if it's a net-new setup.  

If I go through the process of enabling it via the app it fails (it's already enabled on the router so that's perhaps not a surprise).  If I disable Circle on the router and then use the app, it still fails, but with a different error.  

"Something went wrong please try again to enable circle".  I've deleted the Circle app, tried again, no joy. 

It was all working fine until sometime recently - I have no way of knowing exactly when it stopped working. I can only hope my kids haven't been accessing content I don't want them seeing!  Not a happy customer. 

I'm reading elsewhere on the internet and in other forums that a firmware update may have broken it.  There was a firmware update a few weeks ago - perhaps this is the issue.  I'm running V2.6.2.104.

I have a paid Circle subscription I cannot use, and I have two young children I can no longer protect while on the internet - the primary reason I purchased NetGear...

Any help will be greatly received.  

Thanks
DB