i have been happily using OpenWrt 19.07.5 (Linux 4.14.209) on my wrt1200ac for years. [OpenWrt 19.07.5 r11257-5090152ae3 / LuCI openwrt-19.07 branch git-20.341.57626-51f55b5]
some devices just plain can't see the wifi in the scan list so there's no way to connect. note that devices that can see the device one day can't the next and vice versa
some devices that can connect cannot seem to obtain a dhcp address. at least that's what the devices/clients seem to indicate
i'd like to help get these issues resolved, if i can, to help contribute to the community. so let me know what i have to do.
if your router is impacted by the DSA change then during 19.x -ยป 21.x upgrade settings cannot be kept and will require configuration from scratch. did you follow this process described in the release note?
A forum search for "WRT1200AC DSA" (alternatively WRT32x or WRT1900) will certainly yield some useful information for you (you are not the first and only one with this probem ).
I actually performed the upgrade correctly which was good news.
I was able to figure out what the actual problem was.
It seems if I enabled WPA3/WPA2 mixed mode then:
with protected management frames enabled some devices couldn't connect
with protected managment frames disabled those aforementioned devices could connect but other devices were unable to see the SSID at all much less connect to it (probably because they require protected frames)
Downgrading to WPA2 only mode (CCMP forced) with protected management frames disabled fixed everything.
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