Its definitely your internet connection though it could be any number of things specifically some being things you could do to improve it, ie kick off anyone using up all the bandwidth, use wired and not wireless to the router if that's what you use.
Sorry you can't get on to play though, I don't like it when anyone has connection troubles with the server just that there isn't anything I can really do about it short of changing server location and throwing more money at. Which just not going to happen for a while as the current host fits the bill on all fronts right now.