Recently, I purchased a GT-AXE11000 router (new from amazon) plus a used RT-AC88U to use as a mesh node.
After nearly six months running two GT AXE11000 in AI Mesh config, I finally solved the issues with connectivity on the Samsung Galaxy 21/22 Ultra in addition to rock solid 6E and 6GHz performance.
I recorded this video https://youtu.be/qikbVRCRJBw
1) Separate Bands (no smart connect)
2) Use same SSID on 2.4 and 5GHz, and different on 6GHz
3) Use WiFi radar to find best control channels on 2.4, 5 and 6GHz frequencies. Your neighbors' networks are wreaking havoc.
4) Set roaming assistant to boot client at -70 or -75 Db
5) Set static IP and turn off randomized MAC on your mobile device
6) If fixed placement devices are jumping between mesh nodes then bind each device to the closest access point.
7) under wireless professional set Bluetooth coexistence to preemptive.