alisam:
I'm with Vodafone VDSL and only have one router.
Could be your problem. I've found that the ones supplied for free are usually rubbish.
Having had two Telecom modems which give many problems with rebooting, data transfer slowing down to <1mb/s and then fail I bought myself a Netcomm NB6Plus about 3 years ago and have never had any problems since.

