@STN Hmmm... Japan version? :) In the meanwhile, I installed beta firmware. I confirm: it resolves wifi issue. But also noticed: wifi range is much worse than before (on official firmware)...

@STN Any other firmware? I want to install today evening beta firmware, but... Have you got any other one? From where did you download it?

@STN Good news :) I've got the beta firmware also, but I will install it after weekend. Any changes in system log after reboot?

@STN I can check this (log after next reboot) during next week. Actually I am out of home. But you are probably right - twice wifi initialization during reboot may be solution, but I don't have idea...

@STN There is my log (anonymized my MAC address list and IP :)), but everything is ok after reboot): 2021-02-23 13:33:09 led-controller[1102]: <6> 288051 Start to run WAN1_ON 2021-02-23 13:33:09...

@STN No, never changed. But imo - the simple test should show you if is it a problem. Factory reset with the only simple changes for your internet provider (in eng. lang. of course) and with...