working from Home Network setup

Hi there,
I'm totally new to the networking world and I have some questions about a possible setup:

here's a simplified version of the current situation:
https://imgur.com/wIdvg5q

The issue that I'm having is that I will need the workstation to be on the same network of the Nas.
BUT

1. The only socket I will be able to reach is the - A
2. EdgeRouter, according to the docs I've received when working from home, needs to be plugged directly into the router, and it will create his own things ( subnet and his own DNS thingy that I do not understand) to give me access to a secure machine elsewhere via teradici.
3. Plugging workstation PC 1 into EdgeRouter_X gives me internet access ( as expected ) but I'll be on a different subnet.
   

what will be the best way to work around this?

My idea was to get a small switch which will feed the "A wall socket" so that I can plug EdgeRouter and Workstations into the switch. Will that work?

Thanks for your help,

All the best,

Ivan