I'm pretty sure that your router can handle the connections for Gnutella. If not then go back to an earlier (pre Torrent support i.e. <4.13) version.

another thing is just limit the amount of simultaneous downloads/uploads, so your router can handle it. Make sure you disabled UltraPeer capabilities as well.

I used to have a crappy router myself, but got fed up with it and switched to a newer better one.