Same when listening to play music and trying to acces notification bar. Need to reboot everytime, can't use the phone.
Rolling back to 12.12 solves the issue.
On my mi4, I had a lot of wireless loss problems with the first miui 6 releases, I had to rollback to 4.8.22, which is fast and stable.
Is the fix "Some devices often lost signal after 4.8.27" for this problem ?