@Marvin_S Thanks for your kind assistances. I have replied to the email from Tp-Link Support.

@Marvin_S Yes I use Wifi Analyzer that can show the frequencies. The Archer X75 V2 if in ethernet backhaul (LAN wired) it operates at 160 Mhz channel width (the main router is set at 80 Mhz cahnnel...

My main router is BE550 V1 firmware 1.0.11 Build 20240807 rel.25691(5347) and I have two Archer AX73 (version 1 and version 2) and 1 RE705X in easymesh setting. I have one iphone 13 Pro Max which...