tompa94501 Which Operating Ststem are you using? If it's Win XP then XP also has its own firewall. And if XP do you have SP2? SP2 reduces the no. of simultaneous connections.

Can you tell us your Connection type, & Modem & router brand name & model numbers?

Some modems & routers have their own firewalls which generally use NAT. NAT reduces the ports available for incoming. Though this shouldn't affect your dwnlds I believe sometimes it can on some device set-ups.