Try 30.30.30 reset. Hold the reset button for 30 sec. while plugged in. Then while still holding the reset button , unplug the power cord from the router for an additional 30 sec., then still holding the button, plug the power cord for the last 30 sec., and release it. Everything should reset to the default settings. Let me know if it worked.

Sounds like a power supply problem. 1: Replace the power adapter with one equivalent to the original to eliminate a bad adapter. 2: Open the adapter to see if you have swollen capacitors (cap) , if so replace it or them. 3: Open the router carefully and make sure you don't have swollen caps. If so, replace them. You can tell a swollen or bad cap by looking at the top of them. It should be flat. If the tops are round or bubbled , place them. Also look for burnt or deformed components and place them . Let me know if that helps to narrow down the problem . And let me know if the problem still exists .

Open the router carefully and make sure you don't have swollen capacitors. You can tell a bad capacitors by looking a the top of them. They should be flat NOT curved. If they are bad, replace them. Also feel around the board and make sure nothing is getting hot. If so check the components in that area for replacing them. Let me know what worked or if the problem still exists.