Many apologies for late reply.
*
OSX Firewall settings for Tiger IF it is turned on, though you say it is turned off.
* I cannot figure out if your AVR-8000 is a modem or router. Try connecting directly using the AVR-8000. If still no good, try connecting directly using your AirXpress. Also see
Apple Airport Extreme/Express for Mac users * (NAT-PMP)
If you do need to port forward the Airport then first & most important step is
Setting up static ip for OSX & choose port 64049 or 4915. Then use same port here
Manual port forward instructions & sample image
* Also see (a)
If LW Will Not Connect,
__ (b)
Problems with the search,
__ (c)
Hostiles List
* Under LW's settings, preferences > Advanced > Firewalls, change both connection & listening ports to the same above such as 4915 or 64049.