Comment 9 for bug 1454717

Had the same problem several months on my Lenovo G500 with BCM43142 looking for solutions but nothing. This week read a solution on another thread (https://bugs.launchpad.net/ubuntu/+source/bcmwl/+bug/1405074), gave it a try and it worked.

I downloaded the binaries for 6.30.223.271 (from http://www.broadcom.com/support/802.11), uninstalled my current driver, installed the new one (follow the readme https://www.broadcom.com/docs/linux_sta/README.txt) and it stopped the unstable wifi and disconnections. I hope it will continue like this, 3 days have passed and everything is still okay.