@TP-Link correct. Considering that the M5 are all connected via Ethernet backhaul and wireless devices are 1m away and no other traffic on the LAN, why the slow wireless speed?

As you can see from the attached screenshots the Router speed and Deco Speed test show ~100Mbs/100Mbs up/dn speeds however the Deco WiFi Assistant (on phone) and OKLA Speedtest on wireless laptop...