Hi Pax,
Sounds like your connection is fine. LW has the ability to push through some firewalls. Your Motorola probably has a nat firewall in it. You can configure it for LW, instructions at this site:
PortForward.com - Free Help Setting up Your Router or Firewall, be sure to set up a static ip. This may help your speeds.
Your slow d/load speeds could be caused by other things. Is it slow only during certain times of the day? Possibly your isp is traffic shaping you at peak usage times. Could also be caused by the hosts your d/loading from. If they have a poor connection or a lot of people are uploading from them, they might not have much bandwidth to go around. People are constantly logging on and off the network and d/load speeds tend to fluctuate.
You could try some of the fixes in this thread:
Fixes for Limewire when LW isn't operating as it should!