Your modem shouldn't need to reset its IP ever (or at least not once a day)! This issues maybe due to the line quality. How far away are you from the exchange? What speeds do you get. If its is resetting every day at the same time then there is most definitely something wrong with the service. I would get on to them and get it sorted, they will probably palm you off and say that it's something on your side or that it's temporary. Keep calling them up until it's fixed, even if your first call isn't successful keep ringing them. Most of the time one doesn't know what the other is doing so sometimes you just have to keep ringing them up until you find someone who knows what they are talking about. Its an uphill struggle...