I am having this problem with my tp link router for a couple of months, sometime when i restart it or cut the power, the power led, the sync led and the internet led power up and stay on with no connection. It doesn't sync and doesn't blink just a constant light. It works again after couple of restarts. But now it stays like this even after many restarts.
I am planning to hit the reset button and i have my dsl config but is there a way to save me the trouble?
yeah theres a backup button.
as i already suggested you can retrieve your password.
check my posts here.
i don't know if additional data is required to reconfigure your modem after reset. so proceed with caution !
good luck.
I have my ogero password and the router password and i took screenshots of my modem config so i should get everything right again.
I think the dsl router is dead because it won't even reset!
ouch tp-link routers aren't that good, i had to change 2-3 in a year...
My TP-Link has been with me for 2 years so far and I'm loving it. Great for gaming, wider range, no random disconnections (unless if it's from my ISPs' side)

The only issue I encountered was the limitation of 8 connections at a max, fortunately an update came out letting us connect up to 24!