Start from AX10000:

1. From GUI internet Speed test, it shows 1G download speed (which is expected) and 24Mbps for upload (which supposed to be same 1G, testing directly with ethernet on main router ATT BGW320

2. ping from AX10000 to intetnet GW or client, or client ping AX10000 GW, even internal LAN direct link would be over 1ms and has spikes >20ms every 15-20 ping. Which the expected latency should be less then 1ms and no spikes.

Client with Eth connectivity ping to internet GW: 

827 packets transmitted, 827 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 0.517/2.481/34.681/4.000 ms

RE815X with router OneMesh

1. slow speed tested on client (iPhone 15 pro max) with ATT router wifi before "upgrade" to TP-Link setup, iphone can reach to 700Mbps up and down vs. TP-Link OneMesh with RE815 175Mbps up and down, standing right beside wifi extender only getting 300-400Mbps.

2. Tried Access Point mode with ethernet connect as AP, still very bad result

3. ping from AX10000 to APs having the similar latency issue, Round-trip min/avg/max = 1.722/4.808/64.421 ms | Round-trip min/avg/max = 2.460/8.237/167.593 ms

TBC: Still trying different things, but this is probably last TP-Link product I would ever buy again