I've had my fold 3 since launch day and have suffered from horrible wifi connections.
I'm using a 2 pick Nest wifi system, I've tried reaching out to Google and was good it must be this device because none of the other devices on my network are having issues.
I've done multiple factory resets, **bleep** I even changed to a Pixel 6 and stopped using it for 3 months. I then did a factory reset and after 2 full days of usage same issue appeared.
You might want to buy a two in one modem router, use a cable company carrier or cellular company carrier for wifi with equipment. You can also purchase a mobile Hotspot. That might help with your phone connection issues.
