@1382-837366__71 This router model (TL-WR850N) is not supported by the Tether app - here's the tether compatibility list.

@DanQo I guessed that you want to limit the bandwidth of a particular device which is a different feature - Bandwidth Control. That's why I tried to explain what QoS is and how it works. TL-WR820N...

@NGSC Check this post which gives an answer to both of your questions.

@DanQo You need to understand what QoS is: "The QoS (Quality of Service) feature allows you to prioritize the internet traffic of specific devices to guarantee a faster connection when you need it...

@RichStaf If I understood correctly you need a different DNS server on the LAN side of the TP-Link router. If that's correct you can do that here:

@kingboa The issue is that TL-WR902AC doesn't support DFS channels and if you want to use it in a setup like this, you'll have to avoid these channels on the FritzBox 7590 AX.