wifi freezes the laptop (yoga3, u15.4)

wifi works with the 15.04., still, it freezes the system quite a few times when I switch from one network to another
very unstable

laptop: lenovo yoga3 pro running u15.4
the network card is
01:00.0 Network controller [0280]: Broadcom Corporation BCM4352 802.11ac Wireless Network Adapter [14e4:43b1] (rev 03)
 Subsystem: Lenovo Device [17aa:0623]
 Kernel driver in use: wlv

please advice

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also,
bluetooth seems to work as a tool, still,
. it finds my envaya denon bluetooth speaker
. but it can not connect to it
same with my phone

pleaase advice