RD via IRDA requires ethernet cable plugged in

I was connecting from work to my home PC (via Remote Desktop; XP Pro at
home, Win 98 at work). Now a firewall blocks almost every port (at work) and
I don't want to run my RD server on port 80.

So I've decided to use my own gprs connection.

But I would like to unplug my work PC when I'm connected via GPRS.

Here is the problem: if my ethernet cable is unplugged, then the RD
connection fails (time out). If, instead, the ethernet cable is plugged in,
the RD client succeeds in connecting to my home PC.

Please, note that when the ethernet cable is unplugged, I can surf with no
problem with Internet Explorer.

As a further (strange?) note, once the RD connection is established, I can
unplug the ethernet cable (I'm writing this post with the ethernet cable
unplugged).

So, it looks like the ethernet cable has to be plugged in just when the RD
connection starts. Once connected, the ethernet cable can be unplugged.


Thanks in advance for your precious thoughts.