you can access it using the camera's IP address locally, and default login username and password are both admin. if admin doesn't work, maybe you've changed it when you access it on the camera app?...

Can't understand very well of your language. Can you write in English?

For your first question, I suggest you to contact tp-link support at support@tp-link.com for help. I don't think there is a performance impairment to leave the extender with a dynamic IP address.

I find your current firmware is the oldest one. The last second firmware is of the new web design with QoS. So no other firmware for you to update now. How do you tell the ping is high when playing...

There is a troublehsooting FAQ for a similar problem. You may have a try. http://www.tp-link.com/en/faq-691.html Besides, you can try to fix the channel of your router. Move the extender a little...

There is a reset hole on the bottom of the extender, press the reset hole for 2 seconds with power on. This is reset the extender to factory defaults. Here is a FAQ you can refer to :...