Salut, the os 9 version of LW cannot be promoted to ultrapeer, so that leaves out that possibility. You said previous versions worked. You can get them there www3.limewire.com/download/

to setup the router/firewall
if
Behind a firewall: open the port 6346
and/or
Behind a router: open and forward port 6346 to your computer (ie 192.168.1.100) and in preferences of LW -advanced-force ip- check the option and select the 6346 port.

Bonne chance