I have two PCMCIA wifi cards: a Xircom CWE1100 (uses the Cisco 340
chipset) and an SMC 2632W v3. I'm running GNU/Linux with recent
kernels (2.4.25prex or 2.6.1). They're both 802.11b cards.

I have a USR 8054 wireless router which I'm only using as an access
point; I'm using a DLINK-604 as the router and DCHP server.

Everything is fine with the SMC 2632W card. With the Xircom card,
initially I was getting very strange behavior: it was assigned the WAN
IP address rather than a NAT address. The USR 8054 is configured not
to do DCHP at all, and the DLINK-604 is configured to assign addresses
in the 192.168.0.* range. There does not seem to be any setting such
that *any* DCHP server should assign the WAN ("real") IP address!
Furthermore, when this happened, my computer was totally exposed to
the Internet--i.e., all ports were accessible from outside, even
though the DLINK-604 is supposed to act as a firewall (and in fact
does for every other network card).

syslog shows that the DCHP server on the router was, in fact,
assigning my card the WAN IP address. It wasn't the situation where
the DCHP client can't get an address so it defaults to 'last known
good'--it was successfully getting an address, and it was the WAN
address. Bringing the card up and down just gave the same result.

So that was strange. But then it got stranger.

Now I can no longer see my home WLAN at all with the Xircom card.
Instead, I'm getting connected to a WLAN somewhere else. I'm not sure
where, but the essid of the LAN is two blocks away--at least 100 or
more yards. No matter what I do, I can't see my own LAN which is just
a few feet away with the Xircom card. If I put the SMC card back in,
everything is fine.

I've tried network scanning with airtraf
to try to find my own LAN with the
Xircom card with no luck.

I've also tried calling USR and DLINK, but they have been no help at
all. The DLINK people told me to just turn my router on and off.

I have no idea how to even debug this further. I'm pretty sure there's
nothing wrong with my configuration. I'm using the latest firmware for
both routers. The wireless router is configured to accept 802.11b or
g, but both cards are b.

If anyone can even give me some ideas as to how to move forward on
this, I would be very appreciative. Or if there's another forum where
I should post, please point me in that direction.