Is there a Firewall blocking my other network?

Hi CrimpOn 

It was a fair assumption, and 'correct', in that the ethernet is connected into a powerline adapter.  This allows me to place the Orbi in a corner of the house (room), and the Satallite upstairs/otherside, giving fairly reasonable wifi coverage.

Ultimately, you are also correct to question the number of devices.  Given the challenges, it would be more sensible to simply 'bite the bullet' and reconfigure using '.0'.

As I will reconfigure, it is not relevant, but ... the Synology NAS communicates with IP cameras, having static IP, as well as being a media server.  I also found I lost https from '.1', as the ceritificate is tied to a domain associated with the ISP router IP (as provided by Synology) ...TBH I still haven't worked out how it resolves the address, allowing me to access the NAS from the .0 network using the URL.  I thought it must (inefficiently) route via the internet, but I guess it must use something other than DNS as I don't have port forwarding configured...:smileyfrustrated:

I was hoping to learn a bit more about networking and firewalls, but I concede I was over complicating the situation and should stop hassling you guys :smileyhappy:

Although I am likely to reconfigure as per your suggestion, I will accept FURRYe38 as the answer to the initial question (which I still need to sit down and fully understand!).

Thanks again for your time, it is much appreciated.