Wright: Yes, it's not a new stargate it is in fact a very old stargate,
it's the prototype.
[...]
Wright: It has a limited range, a far more limited range than the Milky Way or Pegasus Galaxy stargates. For example, if the Destiny is travelling through a galaxy it can't go anywhere in that galaxy, it can only go within a limited range, that's why they put it on a ship, so as it moves through the galaxy it can move across it and explore stargates that have been seeded by other ships prior to the launch of the Destiny who knows how many hundreds of years before.
http://www.moviehole.net/200920241-m...-universe-cast