W2K3-SP1 router blocks FTP packets

I have two servers running W2K3, and acting as routers. When Microsoft
created the SP1, I of course updated my servers. But very soon, I had to
reverse this operation, because FTP packets where blocked.

I had no problem with any of my other W2K3 servers upgraded to SP1. And for
those 2 servers, I only found a solution two weeks ago. Thanks to a post
about NAT into this newsgroup, I run once the following code, and everthing
works fine now. It seems as if a variable had been forgot for initialization
somewhere into the routing service.

netsh routing ip nat add ftp
netsh routing ip nat delete ftp
net stop "Routing and Remote Access"
net start "Routing and Remote Access"

My routers are DELL/GX110 computers, with 660 MHz processor, 512 MB ram,
raid1 IDE disks, and DLINK/DFE570TX network cards. They also execute DHCP
server, and WINS server. When I installed W2K3-SP1, they still could route
active FTP packets, but the common passive FTP packets where blocked.
Futhermore, NAT is not implemented, and this renders the remedy still a bit
more sorcerous.
--
Bernard Tondeur