T440P Wifi - BIOS downgrade?

[Tosh78]

Hi all,

I have recently purchased a T440P and I'm very happy with this machine. However, the wifi card doesn't work on 5 ghz networks. Since I want to replace the wifi card I know there's a whiltelist in the BIOS. My current BIOS version is 2.37. I've read that in version 2.36 there's no whitelist and I'm thinking of downgrading. When looking at the Lenovo website, I can see two 2.36 files available: gluj26us.exe and gluj27us.exe. Due to the country where I live, I cannot find whitelisted cards available without having to wait for a month.
So before I go the downgrade way, I have the following questions:
1) Is it really true that there's no wifi whitelist in BIOS version 2.36?
2) If so, which of the two files should I use?

Thanks in advance

[RealBlackStuff]

Supposedly the gluj27us.exe has no WL, but I have never tested that.
Just in case: I'd use the gluj27us.iso and a USB-stick or CD instead.
My T440p has BIOS 2.53/1.12 and works fine on 2.4 and 5 GHz with the official FRU 04X6007 (AC-7260).
To get rid of the wifi-whitelist: https://notthebe.ee/blog/removing-the-wifi-whitelist/
After that you can also use AX200/AX210.