Is it my router or my internet provider ???? Please Check here !!!!?

hi , i live in a third world country and internet really sux here . my internet speed is 256 kb/s but the good thing is that its unlimited , i can download as much as i want . i got problems with my router so i got a new 1 , TP-Link TL-WR741ND 150 mbps . everything was ok untill i started to download a game from the internet . every few minutes the download rate goes down to 0 kb/s for like 15 seconds then it goes back to normal . so i entered to my routers page and i watched the traffic , what i discovered is that after every 5 MB that is downloaded from the internet its disconnect and connects again ( its PPPoE connection and i set to connect automatically ). i called my internet provider and he told me thats its my router , it is limited to 5 MBs and that if i download files larger than 5 MBs the router will disconnect every 5 mbs but if i download files less than 5 MBs the router will never disconnect and indeed that is right it will never disconnect . but i think he was lying about the limit thing and he said that there are routers that have 10 MBs limits and more ....... it really sux because all videos on youtube are more than 5mb , when im watching a video the buffering stucks when the router is reconnecting i can't watch a video properly and i also cant dowload properly ...... i really think that he is lying cause i download too much and recently he was claiming about how much i download although its unlimited ........ what i want to know from you is that , is it true that my router has a 5 mb limit for download ???? or is he lying , and he made that for me so he can save some bandwidth for other costumers ????? please reply i really need to know asap . Thank You .