My sister needed a new router when her last one failed. I got her a DIR-816L on clearance at Staples. Seemed to work well at first but after a week or 2 it had no internet connection, never had this problem with the old router. I went to her house and my phone connected to her wireless but I couldn't access anything on the internet, the internet indicator on the DIR-816L was not lit. I power cycle rebooted her cable modem and the DIR-816L and still had the same problem, no internet. I disconnected all the wires, there is only a RG-6 coax on the modem and an Ethernet cable from it to the router and the power cables. This time I had internet. A week or 2 later, same thing, I went to her house and repeated the same process, same thing, no internet until I pull all the cables. This time I changed the Ethernet cable thinking it might be bad. A week or so later same thing. Repeated the same process and it worked. It happened again last night. They power cycled everything to no avail. I went over, walked in had WiFi connection but no internet again. This time I only pulled the Ethernet cable out of the back of the router, pushed it back in and the little globe internet LED indicator lit up instantly and the internet was working. I told her to just pull the Ethernet cable out and push it back in next in to see it it starts working again but she has had 2 strokes so likely won't remember.
I've never run into anything that a power cycle reboot didn't reset, until now. It's as though the router refreshes it's connection with the modem when the Ethernet cable is replugged but I would think a power cycle reboot would do the same thing. Anybody ever run into this issue with the DIR-816L before.