Modem port forwarding rules get cleared

[Guest Gordouxx]

using server 2003 R2 with single nic.

We have a recurring problem with our modem/server setup.

Its a Dlink 504T (gen2).

I've opened ports (in the modem) for SMTP, web server, secure server, and

remote web access (25,80,443 ,444)

But they keep clearing, every 24 hours. So I have to reinstate them, then

reboot modem.

Have replaced original modem (504T gen1)... same problem.

i have also encountered similar issue on 2003 R2 evaluation test bed server

also using 504T.

It seems to me that the server is doing it somehow, any thoughts folks ?