Not yet but once I'm home I can.. I already see some problems in yours. Enable 160 MHz to start with. Also since you set 5 GHz only for the SSID 20/.. MHz setting doesn't make much sense.
I don't have an Mi 11 ultra nor the Ax88U.
What I have is an Mi 11 and an AX92U also an AVM 6660 Cable, on both set to Wi-fi 6 I get an dl speed of over 128 MB/s.
Ok. Long story short the developer team doesn't support disabling Miui optimization.
If you want that, you need root and disable manually with a prop. Good luck.
I watched some movies in 4k, the drain is fine for that. Also like I've told I don't use battery saver of any sort. If I let it idle the drain is <1% too. This is not about letting the phone idleing but using it right ?
As always, battery life is not something generic, it depends on your devices setup, the way you user your device, apps etc..
I cannot confirm that, getting 11h+ SOT on WQHD 60 Hz, and 8h+ 90/120 Hz. Ofc I can kill the bat in 6 hours too.
Go to play store and install SetEdit.
Change your refresh rate to 120Hz, open SetEdit, and scroll down. Look for user_refesh_rate, click on it and change from 120 to 90. Done. It will survive reboots.
It always depends on how you use and setup your phone. I can get on weekly 10h+ SOT, WQHD 60 Hz. No battery saver or anything like this. On 90Hz or even 120HZ 8h+ is possible.
Try a different cable, also don't use USB3 ports in windows when possible. As a note unlocking my Mi 11 with a Xiaomi cable didn't work in windows. The same cable doesn't have problems in Linux whatsoever.
I cannot confirm that. My Mi 11 is fine with AVM.
What you see is most likely a configuration issue in your network.
Traditionally the Fritzbox will configure 5 & 2.4 GHz with one SSID.
Now depending on your smartphone settings, eg: quick switch AP or connect to best Signal/AP the smartphone...