Losing Internet Connection Netgear DGN2200?

I have a Netgear DGN2200 router/modem and have been having this problem for a while now. Every so often the internet will cut out for roughly 30-60 seconds. There doesn't seem to be any pattern to the connection losses and they can happen at any time in the day (overall it seems to occur every hour and a half, although it can vary). When the internet connection is lost, the little "!" triangle appears at the bottom right. I still have wireless access to the router itself. It also occurs on both my wired computer and the wireless computer. On the Netgear itself, the internet light will either flash rapidly green, or sometimes turn red for a short while. The Netgear is plugged via a splitter into the telephone socket. the old neatgear we had did the exact same thing before it finally died and no longer worked at all. Hence why we replaced it with this one. I also rang AOL about the problem, who said that there may be a problem with the line and that we should ring BT about it. We had the line checked and apparently the line was fine and was not the cause of the problem. Things I have tried include changing the router channel and I have tried changing the splitter in case that was faulty. Do you think it could be a DSL problem on AOL's end? It's possible that the drops coincided with a free upgrade they gave us for faster internet, although time-wise I'm not entirely sure.