My FP3 had to go to hospital and came back with Android 10. All working fine, except it refuses to authorise one wifi network. I have a router in the house and an adapter and extender in my cabin office. It sees and connects to my router direct, but when I try to connect to the extender, a TP-link 483, it sees it, but refuses to authorise it. Other devices work fine on the extender. Any clues would be appreciated.
Rob
Not helpful for you but I have this issue as well. My extender is Netgear and as you say other devices have no problem.
This issue reads different symptons then in the post of above link. Just to stress it: if it were the loss of the submenu to choose between 2.4Ghz and 5Ghz, imo the access point should not even be visible.
Probably this is not even related to Android 10 upgrade after all: in this forum are older reports that FP3 dislikes the more exotic and higher channels on 2.4Ghz as of channel 12+13(or sth like that). It feels possible that your access point negotiated with the neighbouring wifi to send on these channels. Same sounds valid for 5Ghz access point. You can try to force your repeater to send on channel 1.
Follow up question: are both access points named the same way? It might be worth a try to name them differently.
Good luck!