After upgrading to the latest firmware of ewelink switches, all switches refused to connect to my ubiquity AP6 hardware. When using an old wifi AP with same SSID, all ewelink switches were connecting immediately.
After swapping firmware on Ubiquity without success, the solution was simple. Disabling the co-existing of wpa2 and wpa3 but force wpa2 only, resulted in all ewelink to connect immediately. As pc’s didn’t have issues, it looks like a bug in wpa3 implementation.