I have Ubuntu 14.04.3 on a Dell Studio 1558 laptop with wi-fi adapter Broadcom Corporation BCM43224 802.11a/b/g/n (rev 01). My home modem/router is an EasyBox 803.
Suddenly my Ubuntu doesn't even show my network on the list. It normally shows and connects to other networks and my phone normally connects to this network.
Strange clue: I tried booting to a live Ubuntu 14.04.2 session on my laptop and it works as expected!