After upgrading for to 1.3.5 I cannot set Wi-Fi to AX only mode I even hard reset the Router But it didn't work, but this didn't happen when firmware version at 1.2.6.

Yes my isp is hinet too

@Clayton87 Is your ISP HiNet? and maybe you can try disable the smart connect feature to let device connect to 5GHz

@Sunshine thanks for your reply I be set bandwidth to 160MHz but the problem still remains. at the Tx/Rx rate is at 1201/1201 And there's no other device connected to the router when speed testing....

The problem happened after upgrading to 500/500mbps plan I found that the WiFi upload speed cannot ran up to 500mbps but that's so strange cuz I've seen others ax73 and can run up to 500/500 with...

@Sunshine laptop can run up to 500/500 in the same condition. The Tx/Rx Rate is both at 1201/1201