Sound like faulty. IP addres obtained on your PC is 169.254...? Keep hold the reset button for 15 seconds. If it won't help, it should be faulty. Is it still under warranty?

It is a computer issue. Try to google it online....

What's the connection speed between the adapter and router? What's the operating system of your PC? Try to update chipmaker's driver. https://wikidevi.com/wiki/TP-LINK_TL-WN823N_v1 Try to install...

There is an instruction to configure bandwidth control. Just follow it to give a try. http://www.tp-link.com/en/article/?faqid=557

You can configure access control to forbidden some websites but https websites cannot be blocked.

How did you power off the router? Unplug the power adapter? Or press the ON/OFF button? Leave the Wi-Fi on, reset the router to factory default settings, power off the router and power it on. Now...