Connection drops when in PPPOE but ok in Bridge mode

Hi. Im using a Dlink 2640b adsl modem+router. I am having this problem for some time. I put my connection on pppoe mode. The connection stays fine for an hour, maybe 2 or sometimes it remains for 5 hours. After than, the green light becomes solid and then goes off. I have to restart my modem to get my net back.

I tried switching to bridge mode and dial from my pc. The connection then doesnt break and is fine. But I dont want to dial. Does anyone know where the problem might lie ? I will flash a older firmware tonight, but i really need to know if anyone has a solution to this horrific problem.

Before anyone blames my router, I used a Huawei modem before. It had the same problem. I gave that router to my bro in law, and he used it saying it was working fine. I even took out a new telephone line incase there was a problem with the line. MY net provider says there isnt any problem with the line. HELP !!!

 

Im in Dhaka, Bangladesh. I use the government BTTB 1MB line. Mine is a wireless router. I dial through the router. If I dial from the computer, the line stays good. Its only when I dial from the router, the line drops

 

doesnt work