Dear Normis,
I am very glad that you paid attention to my problem. I fundamentally disagree with you. This is not a special case. Read reviews on yandex market, nag.ru and so on. Also pay attention to the branch in this section: http://forum.mikrotik.com/t/rb4011-wlan1-disabling-itself/125605/1
This only happens on RB4011 5ghz. On other devices, this is not. This is a QCA9984 chip issue.
my ticket is from February 2019. I get all mikrotik devices from local distributors in Tashkent.
They listen to my conclusion about devices.
The situation with RB4011 5ghz does not please anyone.
PS
I really hope that you will solve this problem.