Depends on what interwall messurment you want/need?? I asked about average network traffic, because I think that much traffic causes your problems with router access. This equipment is for home...

Firmware is the latest TL-WDR3600_V1_130320 like in your post information? How much network/internet traffic you generate on your router?

Thanks for information!

By Ip address is this same symptom http://192.168.1.1

Without tp-link internet access is ok? Do you have any login/password from your ISP?

This is my tutorial for hard reset - LINK