How far is the distance between the rooms? What’s in the way? Concrete, bricks maybe? Because modern mesh networks are very reliable. To troubleshoot it all

How far is the distance between the rooms? What’s in the way? Concrete, bricks maybe? Because modern mesh networks are very reliable. To troubleshoot it all, I’d get a long run of loose laid Ethernet cable and demonstrate that I can maintain a stable connection to two known good switches on either end. I’ve been had issues using Powerline, but as others have said, there are perhaps other issues that I’d not been aware of before! We don’t have MOCA over here in Australia as Coax I. The house isn’t really a thing here!