Issue with 2.4ghz auth (WRT1900AC / mwlwifi / 19.07.3)

I am operating Linksys WRT1900AC with
OpenWrt 19.07.3 r11063-85e04e9f46 / LuCI openwrt-19.07 branch git-20.136.49537-fb2f363

I have a client device apple airport express which can connect only to 2.4Ghz and doesn't support CCMP(AES) cipher...

If i set up on the 2.4 radio cipher Force TKIP airport can connect to router ... but in case i set it to both force TKIP and CCMP or Auto ... the client cant connect... is that a Bug?

Also one more thing .. is that okay that my 2.4ghz radio shows only Bitrate: 57 Mbit/s?


can anyone comment on that issue? thx