On Feb 10, 12:46 am, Jeff Liebermann <je...@cruzio.com> wrote:


> Let me guess. You have a PPPoE DSL internet connection and your
> neighbor with the open access point has a cable modem?

No, your guess is wrong. I have a cable modem. No PPPoE here.

tcpdump on the FreeBSD AP (on the uplink to Comcast) shows no
difference in MTU/TCP segment size when things work and when they do
not work. Using the old laptop (802.11b) shows same packet sizes as
when using the new laptop and a wired connection. Likewise, what
little traffic that makes it using the new laptop (802.11a/b/g card)
has the same MTU as well. There is no fragmentation going on. All
TCP segments show DF.

I bought an AP, plugged its "ISP" port into the FreeBSD switch. New
laptop works fine. (Traffic dumps are same as above).

So, the topology is fine. There is something about this new wireless
card and that card in the FreeBSD looks like the problem.