Wi-Fi stop working after an hour

Hi,

after upgrading to macOS Big Sur I have a problem with Wi-Fi on my MacBook. After roughly an hour of uptime the Wi-Fi stop working – the icon in toolbar goes gray, and there’s an exclamation mark over it. When I restart my mac, it works just fine (for about an another hour), but then another restart is required and so on.

I’ve tried without any results:

• Reseting NVRAM, PRAM and SMC
• Trying different wireless networks (including my iPhone hotspot)
• Forgetting the network
• Using Google DNS servers
• Renewing DHCP Lease
• Using static local IPv4 address (in coordination with setting my mac’s MAC address for that IP on my router)
• Reseting both router and the modem (my mac is the only device using our network that is experiencing this problem problem...)
• Running wireless diagnostic (after first time I’ve tried this the Wi-Fi start running after the diagnostic, but then stopped after an hour)

That’s about it. I thought that it might be Big Sur related issue that is going to have a couple more users, but after a week it still wasn’t fixed by any update and I am not able to find anyone with a similiar issue. I don’t know, if it’s related, but it seems to me that this happens only when I am using ARCHICAD – but I could be wrong, since I have ARCHICAD running almost all the time lately, it’s hard to tell...

Best regards,

Ondra