Compaq Presario C500

My father has a Compaq Presario C500 laptop With a broadcom WIFI adapter. It can connect to WIFI everywhere we have tried (like a dozen places) EXCEPT at my grandfathers home. We have tried 6 other laptops at pops and ALL connect just fine EXCEPT my dads Compaq. It’s the wierdest most frustrating issue I have come across. We have even tried taking a wireless router that he has been able to connect to from my home and taken it to pops…it ‘sees’ the router but fails to connect. We leave WEP off (open). Any uber WIFI diagnosticians that can help?