Let's say there are 2 of them On both is the same sketch with different client SSID. On both, I go through the procedure of inserting SSID, PASS, etc so they connect to a local WiFi network. If they are on some 2 meters, everything is ok. If they are on some 10cm, there is a problem
One of them connects to a local network. The other tries, but fails every time. When I separate them, reset them, everything is fine. Only if they are close. And I have one setup that needs two of them on 10 cm.
Almost regardless of the walls material the wall will reduce the signal strength. So you should do a test with some real walls.
If they are 10 cm with air inbetween the signal strength RSSSI might be -40 dbi. If you put a 10 cm wall between then it may vary between -50 dbi down to -80 dbi
best regards Stefan
The problem is while they are mounted on their places. Wall is made of gypsum board, so not much to reduce strength. This happens only when using the wifi manager library. I tried regular wifi scan sketches on 2 of Wemos, and they work fine in 10cm. The only project with this library when boards are close doesn't work as they should.