Server not found via remote connection.

[Lukes]

Thank you very much!
I will try to apply these settings

[mik_s]

While I understand what you were trying to do now I don't think it would work well isolating the server on a separate network as and device that needs to use UMS will need to be able to find and communicate with it. Seems you had it figured out though thanks to @Boss.

Yes the guest network would be the best solution to isolate your computer from when you have visitors wanting internet access, then there is no need for the 2 networks and the second router can just be used as a switch.

My neighbour set one up for me a few years ago when covid hit and I could not afford to get my own connection, I was using the local library at the time to get online.

[Lukes]

I thank you for your attention and dedication in answering my questions.
I think I was trying to do something similar to what internet providers do, when using another NAT before the connection reaches the external ip, on the internet.
I'll try to set up the guest network tonight.
Thank you very much!