I was able to fix my Wifi. I can connect to 5ghz and the connection is stable. what i did was:
Clear dalvik cache and Cache
Reflash the rom
Flash Magisk Uninstaller (if you have root)
Change wifi router settings of 5Ghz by changing the channel to 124
I don't know what steps fix my Wifi issue. What i do know is uninstalling magisk also fixed my proximity sensor issue.
Sent from my M2007J17G using Tapatalk
The Mi11 has no twrp so cannot clear cache.
Do not have magisk.
Will try with a fixed channel.