I have a Blackberry 9900 updated to 7.1. When I try to use a Sierra Wireless AC763S mifi it crashes when I connect. Have tried other 9900's and they don't crash the mifi unit. I can use my unit to connect many other routers.
Also have issues with trying to synchronize over wi-fi with SplashID Safe and it crashes the PC software so I would say the issue is with my unit.

Have rebooted/pulled the battery many times. Have rest wifi to defaults. Have run out of ideas. Any suggestions?