My Linksys EA7500 was not connecting today. I can connect directly from my computer to the modem and get internet. The router is not able to make a connection with DHCP. When I assign a static IP, then the router is able to connect. I really need DHCP working so I don't have keep changing static IP.
It seems similar to this post:
but I don't have any rogue devices on my network (that I know of).
Did you see my post in that thread that you referenced about power-cycling the modem ?