Your maximum number of connections is determined by the internet connection speed you list in the preferences, though you have to set this number manually when you connect or after disconnecting for any period of time. Except with really fast connections, however, it is hard to maintain this number and have a bunch of downloaders at the same time.

You can get your max by typing in some outrageous number. You get a little warning screen, but then you get the largest number available for your speed.