I had a problem with iPhone 12 pro max and Zyxel access points NWA1123AC-HD The problem was only with 5 Ghz wifi iPhone was always disconnecting and reconnecting again each minute or two or even not connecting at all. Other Non-Apple devices was perfectly normal, other Apple devices was reconnecting but each 5-10 minutes. iPhone 12 pro max with 14.3, other devices with 14.2 or 14.2.1 Access points don’t have WPA3 option, only WPA2, but After hours of trying I switched 5Ghz channels on access points to 20/40 MHz instead of 20/40/80 MHz Now iPhone 12 is also reconnecting each 5-10 minutes, but it’s much more stable than before, or other Apple devices like previously also reconnecting other time, like each 20-30 minutes. Let’s say “acceptable” Maximum speed of WiFi is lowered almost twice, but at least it’s working. Hope it will help somebody Also hope that Apple will fix it in upcoming iOS versions