Behind C2801 router we have a mail server (172.20.17.35) which is avialabe to the outside world and there was a NAT config as below.
ip nat inside source static tcp 172.20.17.35 25 X.X.X.X 25 extendable
We allow HTTPS acceess to the same server and configured another NAT using the same NATTED IP address ( X.X.X,X), it did not establish the connection while it built NAT in the table.
ip nat inside source static tcp 172.20.17.35 443 X.X.X.X 443 extendable
Then, we tried another NATTED Ip address (X.X.X.Y), then it worked.
ip nat inside source static tcp 172.20.17.35 443 X.X.X.Y 443 extendable
Why can't we use the same NATTED IP addresses while it is only a port translation?