@Cawsie Archer AX6000 supports speed test function, therefore the Tether app supports it correspondly. There are some built-in websites which used to test the speed; once you enabled speed test...

@IGraham Lol, great to help you. If need more help, be free to let us know. Best regards.

@Jorj In AP mode, all traffic will be transferred to the main router directly, bypass the main Deco. The first-added Deco is the main Deco, it can help us to add other Decos and make us use the Deco...

@Llaura With the sim card inserted into the TL-MR6400, try to reboot it and verify whether it works. Besides, you can hard reset it by holding the reset hole for 10s with MR6400 powered on. Still the...

@DanielDK I see, sorry for that; you can return it and get a new one first and test its performance. Any further problem, just be free to let us know. Best regards.

@bayad Hello, nowdays, we use mobile hotspot on Windows 10 itself to boost the wifi signal. Below is the instruction: https://www.tp-link.com/support/faq/2021/ May it help.