I checked the online manual of ripwave-mx modem & couldn't see anything about internal firewalls. All I found of interest was: "Do not use the equipment while you are in a bathtub, shower, pool, or spa." lol

If it worked fine for a week & had problems then try deleting your LW Preferences folder whilst LW is closed; instructions here: Point #2 & 3 in Fixes for Limewire (sample image included at bottom of page.)

Otherwise the issue might be your ISP. If still problems, go to LW's menu bar, Tools>Options>Advanced>Firewalls & change the listening port to one between 49152 - 65535 such as 64049. See if the brick wall disappears. You may need to restart LW for it to take effect.