I had the same problem with my BRCM adapter after upgrading to W10 on a Dell XPS 8000.

Initially I rolled back to W7 and the problem went away, but I later found this board with the solution to install the 14.2.0.7 BRCM driver dated 7/20/2010 (the "R282233" download) to fix the problem in W10.

Before upgrading to W10 again, I installed the "R282233" download. Everything went well and the driver seemed to work in W7. Sooooooo....

I upgraded to W10 today and soon began having connectivity problems again. When I checked my BRCM driver, it was 15.6.1.2 dated 1/29/2013, not the 14.2.0.7 I had installed prior to the upgrade. When I repeated the install from my R282233 download, I could not get the 14.2.0.7 to install over the 15.6.1.2 like before. I tried uninstalling, restarting, reinstalling without success. Each time I was selecting the "Modify" option in the Broadcom Installation which worked for me the first time.

Ultimately, I needed to select the "Repair" option in the BRCM install package, instead of the "Modify" option. This overwrote the 15.6.1.2 driver with the 14.2.0.7 driver.

Hopefully  this will save someone some time if confronted with the same issue.