This is not the best place for you request for a feature. http://ticket.tp-link.com/index.php?/Tickets/Submit

Read this post for some clues. http://forum.tp-link.com/showthread.php?77405-Wake-on-Lan-with-3G-router-3G-modem...possible&highlight=wake

Sounds strange but why not just leave it in static IP if it works better....

Upgrade the latest firmware Archer C2_V1_141117, reset and reconfigure it. By the way, there is an instruction for you to troubleshoot. http://www.tp-link.com/en/article/?faqid=785

You should connect only one device by cable or wirelessly to test the speed and compare them.

To change power supply unit won't help improving power supply of the USB port. Y cable should be better if there is one. If not, I don't think it deserves to try because it doesn't solve the problem...