Exclamation point in WiFi, Network Prefs error

I have an intermittent problem where I lose wifi and sometimes I have to manually mess with the DNS numbers, delete the WiFi and add a new one , etc.

But often I get the exclamation point through the WIFi symbol and if I try to open Network Preferences it crashes immediately and gives me a generic “There was an error with Network Preference” alert, or similar.

So all I can do is restart the machine and hope it’s gone when I boot up again.

Often it doesn’t and sometimes I restart in Safe mode, sometimes resetting the PRAM and SRAM, but that rarely works.

If it gives me WiFi symbol without the exclamation mark and I can open it, sometimes I can use an Ethernet-thunderbolt direct line to router and introduce it back to the laptop, but even then, it sometimes doesn’t recognize the connection.

I was sure it was my router switching between 2ghz and 5ghz signals but cleaned up my router so it would switch more smoothly.

it stopped for two weeks or more. Now gone back to exclamation point and endless restarts.

Does anyone have any advice?

Thank you.🙏