I can empathize with you. I must have tried a dozen different
things. This is the one that finally worked for me:

<https://help.ubuntu.com/community/WifiDocs/Driver/bcm43xx/Feisty_No-Fluff>

The computer is a HP Pavilion dv2718us, with a Broadcom chipset. The
chipset was sometimes reported as a 4310, and sometimes as a 4315,
depending on how you queried the hardware.