Hi,
I was struggling in the Wifi connectivity with following syndromes:
1. Having trouble connecting to 5GHz network by default unless specifying BSSID
2. Will disconnect after a day or so
3. Cannot parse RX packet header properly (and will spamming errors in dmesg)
After putting in some efforts, I've found a newer firmware version on GitHub:
New Firmware: BCM4356/2 wl0: Apr 18 2017 13:54:43 version 7.35.184.1.r5 (A2 Station/P2P) FWID 01-efd4ca0d