You didn't tell what kind of connection you have. Anyway, no kind of mobile/cellular broadband is stable enough for the game. That means LTE/4G, 3G, satellite, whatever. Hopefully you aren't trying to play with any of them.
That leaves the wired connections, starting from the good old dialup modem through ISDN to DSL either via TV-cable or telephone line to optic fibre connections. Stability is better than speed in any of these options. I don't know about your whereabouts, but at least here the tv-line connections have had more problems than their telephone wiring alternatives, because they are more sensitive to nearby user activity. The worst scenario I've heard of was an illegal server upstairs, ruining all connections in the neighbourhood.
If all the above is known good, the question is whether you're connected to the router wirelessly. WiFi may work flawlessly in normal Internet usage, but during gameplay anything can disturb the signal. Starting from your refridgerator or microwave in the next room, a slowly failing energy saving lamp, lawn mover next door, a bypassing car with some moist in the ignition system and so on up to sunspots and other spatial electromagnetic phenomenons.
If none of the above can be named as the culprit, check for other internet activity in your computer. Any update downloads in the background can cause warping, although they mostly are quite short. A bigger Windows update like a Service Pack might take longer, especially with a slowish connection. I suppose you don't have any torrent or messaging programs running while playing? E.g. Skype can use massive amounts of resources. Also bear in mind that if your family members share your connection, your gameplay might suffer. Especially if, say, your kids are streaming a movie on tv while torrenting music to and from their pc('s) and your wife is having a video call family meeting on Skype, any regular Internet connection would be on its limits.
