I am not sure about the explorer part. But to access the USB via the router, normally we can type in \\LAN IP (\\192.168.0.1 by default) in file explorer, or type in ftp://LAN IP in the address bar...

What's the model number of your router? The only way to find back the gateway password is to reset the router. And after reset, the router should still have a wifi password which is printed on the...

Is it working on your other computers? For windows 10, this link may help you: http://www.tp-link.com/en/faq-1354.html

Never noticed this issue. You may try to check with Tech Support of TP-Link by email.

On the picture you sent, it looks like the new PA4010 you've added is in a bad position. It have a very slow link speed with others which might have caused the trouble. You may try relocate it to a...

As I know, for the products bought in mainland China, they only have Chinese version. You may need to buy one in your own country to get English version.