If I set the WiFi encryption to WPA3-SAE or to WPA2-PSK/WPA3-SAE Mixed Mode on my Linksys WRT1200AC, my iPhone 12 Pro and iPad 11 (3rd gen) cannot connect. They do connect correctly to another router (Fritz!Box 6660 Cable) using WPA3.
What am I missing?
try disabling mixed mode ....
I did. I first tried the mixed mode and when that failed, went to WPA3-SAE only. Even restarted all devices between tests, just for good measure. No luck. Is there an alternative to mwlwifi?
Mwlwifi and WPA3 don't do well together. When you search the forums, you'll find tons of topics about it. The whole Linksys AC series is affected across the board as they all use some form of Marvell 802.11ac radios (which stopped being supported by the vendor).
Exactly, for marvell use WPA2-PSK only.
Same as on WRT3200ACM.
As already mentioned by @frollic try this:
With the previous version it was also some fiddling with the settings.
Can you try connecting any iOS device?