I use an Archer MR600 as the main router downstairs, two RE200s in OneMesh upstairs and a WA850RE without OneMesh to cover the yard.

The main router is roughly positioned in between of the two RE200s, but one of keeps connecting to the other and since the user is only able to change the main network settings in a OneMesh setup, I have no other choice but to ask someone to simultaneously plug the RE200s with me so they connect to the main router. (Which is obviously annoying!)

I understand that this might happen due to one of these two reasons: 1. Since the SSID is the same, the RE200 mistakenly connects to the closer WiFi. 2. The RE200 is connecting to the other because the network quality would be actually better. (But the TP-LINK website says it is recommended for the REs to be connected to the main router.)

Anyone has any idea how all this works?