Model : TD-W8961ND

Hardware Version : V4

Firmware Version : 5.0.0 Build 120522 Rel.23978

ISP : BSNL

Hi,
I have a TD-W8951ND modem router. My connection is not stable at times. It disconnects and reconnects immediately. I am pasting the recent system log below. The issue happens when I play a youtube video or try to load an image or etc. i.e. Whenever my download speed increases. FYI this is not a constant problem. Sometimes the connection is fine. But, the problem suddenly appears again. At times I can't even download anything since the connection is not stable.

6/3/2016 5:49:26> WANIPConnection->GetGenericPortMappingEntry failed
6/3/2016 5:53:21> netMakeChannDial: err=-3000 rn_p=80544b08
6/3/2016 6:12:12> Last errorlog repeat 23 Times
6/3/2016 6:12:13> WANIPConnection->GetGenericPortMappingEntry failed
6/3/2016 6:14:26> WANIPConnection->GetGenericPortMappingEntry failed
6/3/2016 6:16:11> netMakeChannDial: err=-3000 rn_p=80544b08
6/3/2016 6:22:11> Last errorlog repeat 20 Times
6/3/2016 6:23:36> netMakeChannDial: err=-3000 rn_p=80544b08
6/3/2016 14:9:20> Last errorlog repeat 1336 Times

I contacted my ISP and they said that the line is clear and I have to check the modem. I contacted TP-Link through email. Their reply was that, "Sorry, your modem is out of warranty." I explained them again that I don't care about the warranty. I want to make sure that this is an issue with the modem before I buy a new one. I don't have another modem to test. There is no response from TP-Link after this mail.

It will be really helpful if someone can help me with this.

Thank you.