Internet connection via wifi

I recently purchased a MacBook with M1 chip. Although it claimed to connect to my router I could not get internet. Moreover, I could not get internet in cafes or in Apple store. Genius Bar tested everything and could find no explanation. They reinstalled OS and tested wifi in Store. Took it home, logged into router, no internet. We have never had a router problem, and my wife bought a MacAir recently with M1 chip and she has no connection problems. Suggestions?