Strange WiFi problems

[FryPpy]

I am building ultimate wireless thinkpad now. This is T61 (Frankenpad) with LTE WWAN + 802.11ac WiFi.
For WWAN i have chosen Sierra's MC7304 module and it works well with Middleton's bios right out of the box. I have got 50Mbps dwonload / 20Mbps upload. There is some things to do with this module:
- power management
- voice calling
- GPS functions
But main thing - it is alive.

802.11ac. First of all i've got Netgear D6200 router. Not the best but working.
Initially i have got intel's Dual Band Wireless-AC 7260 module. Thinkpad starts with it normally. But it lacks XP support (yes i am on this OS now and don't want to change this But now i have got Broadcom's BCM94352HMB (Lenovo FRU: 03T7135). It have XP drivers. But my Thinkpad don't want it


Symptoms:
When i start Thinkpad the screen is black and it makes 4 short beeps and no more. Lights under screen works as usual.
HMM - 4 cycles of 4 short beeps - System board (security chip). But i have only one cycle of 4 beeps.
Initially i think something with the memory. But when i removed WiFi - it boots Ok. I have placed WiFi in WWAN (left) miniPCIe slot. And all works Ok. 2 devices appears in device manager (Bluetooth + WiFi). I have installed drivers. Rerouted WiFi antennas (just over HSF - keyboard is removed) and connects it. And old (non ac) wireless networks are working.

QUESTION:
What is going wrong? What can i do to solve this quest?


More interesting things:
- Fn+F5 doesn't see WiFi to turn it on or off
- main wireless switch is still workable. When it is on off position WiFi networks are no more accessible!! (for device in WWAN slot??)

[ecuecu]

Get rid of XP, 802.11ac works ok from windows 7. Check your bios.