wi problem with message > 7400 bytes

Greetings,

I'm having a problem receiving UDP messages over a wi interface:

wi1: <Dell TrueMobile 1150 Series PC Card> at port 0x180-0x1bf irq 11 function 0 config 1 on pccard0
wi1: 802.11 address: 00:02:2d:4a:d8:7d
wi1: using Lucent Technologies, WaveLAN/IEEE
wi1: Lucent Firmware: Station (6.10.1)
wi1: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps

(wi0 is also a 'Dell TrueMobile 1150 Series PC Card' in
 a mini-PCI card, but hangs the system when you try and
 configure it -- so it obviously isn't configured in this
 set up.)

I have a small program that does a trivial UDP test:

  http://people.freebsd.org/~deischen/udptest.c

My results show that:

  o Receiving large (> 7400 bytes) messages does not work.

  o Sending large messages works.

  o Sending & receiving large messages over a wired
    interface (dc, fxp, etc) works.

Am I suppose to be able to receive UDP messages larger
than 7400 bytes over the air?

To run the above test:

  # On one machine, run it as a server (it just echoes
  # the messages back to the client).
  #
  $ udptest -D

  # On the wireless machine, run it as a client (it
  # sends a message to the server and waits for the
  # echoed response).
  #
  $ udptest -D -c -a <server's ip address> -m <message size>

If I set message size to 7392 (plus an 8 byte header
in my message = 7400), everything works.  Anything
higher and I never receive the response.

Thanks