I found out, the core does not choose the strongest WiFi signal for its connection (to the cloud). I running a core in the basement, sending some data to a webserver in my intranet. Logging the Wifi strength, I found that the connection signal only has a value of -70db to -80db. But the core is located within 1m of the access point in the basement. The other access point is on the first floor. If I switch off the AP at the 1st floor, the core switches to the basement AP and measures a strong WiFi signal about -40db.
How does the core decide which Wifi connection to use?