The router is stick to R_00.01.12.3 and the problem with WIFI is still there.
It's a serious problem which definitely impairs usage of this router in production environment.
Sent private message to the support at teltonika and after 3 months no answers, no solutions, no workarounds.
This is my first and last teltonika product, which is allegedly engineered for the industrial environment but obviously is not.
Folks, don't waste your money on this. Go with mikrotik.