I believe the Airtime Fairness option is the important one to disable on this router.

I agree it improved connectivity, but I still had a couple of random disconnects before I disabled QoS, which was the last change I made.
Could be due to my WiFi having 20+ devices & the device type. Can’t say I’m qualified to give a definite answer. 

Can only say everything is working perfectly. Very impressed with the Asus XT9 too. Virtually full throughput on all devices. 

​@Bucko2025 

Glad you were able to get your network working properly. Congratulations!!!

I too have Asus routers in AiMesh which are RT BE96U x 3 in wired backhaul. There are a few settings mentioned that are the opposite of my setup. I have 31 Sonos units and my network can have as many as 58-60 clients active at any time.

What also puzzles me (in addition to the settings below) is that Adaptive QoS has been mentioned before as an issue and co-signed by other members. I guess my network is special  

Professional

Roaming Assistant – ‘Disabled’ _Enabled

Disable WMM APSD

WiFi Channel changed from Auto to Channel 6 _Auto

Adaptive QoS

Adaptive QoS – Disable – change to ‘Off’_On *

 * Adaptive QoS must be properly configured and not just turned on 

​@AjTrek1. Thanks for sharing. My initial post was really a summary of actions I had taken, as I found I had to piece together settings from several sources. I did try to configure Adaptive QoS, but couldn’t get the system stable - it seemed to be random; sometimes the App connected, sometimes not, products were missing when the App did connect. I didn’t investigate further as to the root cause, my intention was to simply get the network working!

I haven’t re-enabled Roaming Assistant as yet, but I'll keep that one in the locker should I have any issues with phones, laptops etc. I do keep looking to see what I can reset, but as the old engineering adage says ‘if it ain’t broke, don’t try to fix it!’

I’m really happy with the system, its solved all my issues and thanks again to contributors here and elsewhere for providing advice & suggestions.

Everyone's network is ‘special’ and unique, ie no two WiFi networks are the same. We all live in different houses, different ISPs, with different APs, located in different rooms, with different devices connected,, different usage, etc, etc

I personally don’t use any of the ‘auto’, QoS or roaming features on my network. I would only consider QoS, if there was insufficient bandwidth with ISP. Let the mobile clients decide what connection they prefer, rather than the AP.

Exactly!