The problem: 5GHZ-2 WiFi network is configured to use 160 MHz channel but after couple of days it spontaneously switches to another channel with 80 or even 40 MHz width. For example right now it is operating at channel 132 at 40 MHz (connection speed is just 400 Mbps). 5GHZ-1 radio seems to be stable and not affected by this problem.

My wireless settings: