[X4U] Can an Airport Base station wear out?

[Jeff Porten]

This has been driving me nuts for a while, hoping someone can help me 
with it.

I have a snow non-Extreme base station at home, NATting my cable modem 
connection to three computers.  The PowerBook G3 has a fixed local IP 
and is connected by an Ethernet cable.  The Titanium G4 has a fixed 
local IP and is connected via Airport.  My AlBook 17" is on DHCP and 
connects via Airport (and always gets assigned .1.4, the next available 
IP).

If it matters, in addition to the 10.0.1.x network from the base 
station, I have an irregular 192.168 network connecting the Titanium 
and the AlBook over a direct wire connection when I need more speed 
than 11 Mbps.

The symptom: my cable modem is silly fast; I've seen peak speeds of 700 
MBytes per second, and it's consistently doing 100-200 MBytes per 
second.  But over time, the speed degrades where it only peaks around 
150 and can poke along at 25-30.  Rebooting the Airport brings it back 
up to snuff; it's rare that I have to touch the cable modem.

When I run an application that causes heavy network traffic, I can blow 
out my network entirely and stop all Internet connections until I 
reboot the Airport.  BitTorrent does this intermittently; what I 
discovered today was that if I tried to run a port scan on a client's 
network (256 IPs, all ports), it'll kill the entire connection dead 
(including the port scan).  Stopping the scan does not resume traffic; 
I need to reboot the Airport for that.

I'm 100% certain this isn't an interference issue; one of the computers 
are connected by wire, and the other two are typically 5 feet away from 
the base station.

What's going on?  Is the hardware dying somehow?  My local Apple store 
suggested that it might be a heat issue, but the base station always 
runs cool.  So I'm just stumped.  Ideas?

Best,
Jeff Porten