I am using master DNS with forwarders, Open DNS and Google name servers and DHCP on my PC; ADSL router is a relay.
My ADSL router (TD-8840T 2.0) has had some strange behavior during the last couple of weeks
After some amount of time (ranging from a few minutes to several hours), when I send a request to a web page (I mean any page like google.com) it loses ADSL (the LED switches off).
I am not sure, but I suspect it restarts.
After a minute or two LEDs come back and traffic continues until the next time the LEDs just go off.
I bought it from my ISP more than 3 years ago.
Wireshark is not showing any unknown traffic.
I can not find what's wrong.
Could it be that its lifetime is up?
I am using my PC 10h daily.
UPDATE:
Called tech support of my ISP. They said to try it without phone and splitter, and it showed the same result.
SNR margin downstream is very low probably due to signal from national telephone agency and that if it restarts I should call them again with values from ADSL part of status panel.

UPDATE:
I made another call to my ISP since router continues to restart.
Caught the restart values in the image below
- SNR margin downstream is negative (-5.-1)?
- CRC 2014

My tech support is telling me they will call the national telephone agency to check out the signal.