@TeeDee1980 According to its specs X20 has an SPI Firewall - more on TP-Link firewalls here. Opening particular ports can be done through Deco app port-forwarding, SIP ALG or UPnP feature. It's quite...

@PidzisBox Here's a guide on how to protect your router from cyber attacks. Here's how you can tweak the DoS parameters of your router. If you're not sure what value to set for a particular parameter...

@Mypinoytaxph Keep in mind that HW v2 and above are tether app compatible and only when the device is in "wireless router mode" or "access point mode". Here's the list with the tether app compatible...

@renansimoes Have you tried to reset the router to its factory defaults and configure from scratch. Usually resetting solves problems of this type: When the router is powered on " Press and hold...

@gen66 Your best bet is to reset the router to its factory defaults. When this is done the QoS settings would be disabled for sure. Configure the router from scratch and test. The FW version you're...

@fammo You got it right. Depending on the device FW, some devices may or may not have so called "WDS mode" setting. Here's a thread which can throw some light on what I am talking about.