I have Linksys EA4500 (Viper) with Feroceon 88FR131 rev 1 (v5l) on OpenWrt 21.02.0 r16279-5cc0535800 / LuCI openwrt-21.02 branch git-21.327.65561-7f37a58
All my devices have connection drop on 5Ghz. My SONY TV, Apple HomePod Mini, iPhone 12, even my Macbook. My AP is close to all my devices so it's not signal strength issue either.
It disconnects for a few seconds. I did not find a solution and don't even know how to debug this
Please try a 21.02 snapshot or master snapshot first, there was a bug affecting mwlwifi and ath9k, which might affect mwifiex(?) on your device as well. While this will be fixed in 21.02.2, it's not fixed in 21.02.1, so you need to look at the snapshots for now.
the official 21.02.2 is not out for hardware revision 1. snapshots don't have UI and I'm a bit of a noob when it comes to openwrt so I was waiting for a release which is not coming?
and this is a ping test. is this normal on 5G and close distance?