XWin fails connecting to XDM for sending wrong source-IP

[norm]

I was trying to connect to a Linux-server (Debian/Sarge, XFree86 4.3) 
from my Windows-box (Win XP Pro SP2, cygwin 1.5.15-1, xwin 6.8.2.0-1). 
All I got was a blank X-screen. I thought it may be a font-problem and 
tried:

XWin -query 192.168.200.200 -fp "tcp/192.168.200.200:7100"

After that, netstat gave me the following two lines on the Linux-box

tcp 0 1 192.168.200.200:1091         192.168.68.1:x11   SYN_SENT
tcp 0 0 192.168.200.200:font-service 192.168.200.2:1596 CONNECTED

where .200.200 is the appserver, .200.2 the winbox and .68.1 something I 
never heard of. If you specify the right source-IP with the -from 
argument, everything works fine.
Do you already know this? Is there any reason for this behavior I 
haven't thought of? If not, could someone please confirm, that this is a 
bug?

Thanks
norm