I don't use any special version. I used and tested Oficiall version or rc versions. The results did not change. The issue you were talking about was about another issue.
Since Wnidows 7 was the OS that device was designed for,
while I am finding issues in web searches - in 2023 I'm not sure they're related. I have also seen some *nix and BSD discussion about the issue.
The Intel Centrino wireless of that era gave me issues on some routers no matter how many different drivers and router firmware/settings were tried.
Only solution was to give and use something else. In one instance that was an Ethernet connection to an old cheap router (DIR-615) running DD-WRT acting as a bridge to the main wireless network.
So far, I have not had any problems with my wifi card, nor do I have any problems with my current TPlink ax1800 device, which does not have openwrt installed.
The chip of my wi-fi card is Intel® Centrino® Advanced-N 6235, Dual Band (2g/5g Supports speeds up to 300 mbps). My os is Windows 10 64bit. There are iphone11 /iphone8plus/xiaomi redmi 9/lenovo new generation tablets in my network. All of them are devices that support high speeds. However, when I turn off the network connections of all of them and test them, the result does not change, the problem continues.
there is no device with 802.11-b-only infrastructure on my network. As I said above, all devices are new generation (I have an old generation laptop with n6235 wi-fi chip)
I wrote about TP-link just to point out that I have no problems with it. I would also like to point out again that I do not have any problems when I install the stock ROM on my Xiaomi 4a gigabit edition device.
I already get 300mbps speed in Wi-Fi network mode, there is no problem with that, the distance between me and the router is 1.5 meters and there is no wall in between. Fluctuation example; I start downloading a file at a speed of 13mb/sec, but 15-20 seconds after the file downloading process starts, my speed drops to 50-60kb/sec. Meanwhile, I cannot access anywhere, including the router. My wifi-router network connection is not disconnected, but it acts as if it was disconnected.
Asus laptop belongs to my brother, unfortunately I don't have it with me right now. I didn't look at the model etc. of that laptop, but it did not support 5G, it was only a 2.4GHz wifi device. Because at that moment I was so angry because of OpenWrt!
Actually yes, this uses your OpenWrt AP. This test would ensure results that generally only test the WiFi chip (AP) and not tax the CPU (i.e. test if it's routing, or just a WiFi chip, etc. issue only).