I asked the TP-LINK about this question also. Here are the answer from TP-LINK support: 1. Routers with USB Ports provide less than 500mA power supply on the USB port. Please check your HDD Drive. It...

Maybe you need to reset all of them to factory setting and leave them as factory setting and then plug into the wall socket.After that, bring them into the same room, all to the wall socket and see...

Disable the WMM or Hardware NAT function on the router?

TP-LINK USB is using Samba not DLNA.The Media server is from USB hard driver: http://www.tp-link.com/en/article/?faqid=340 Due to the limitation of the tech protocol, it is not as good as DLNA for...

Yes, they are compatible with each other even though the hardware is a little bit different. They can work together but sometimes needs the powerline utility to make them communicate with each other.

Yes, Tony. 200Mbps can work together with 500Mbps. They are compatible with each other.