I'm reformulating the question, once the previous provoked a little confusion.
I didn't find a way to subnet
172.16.1.0/26 between two interfaces. MY thought was to set device's gateway to the next device.
R3 - 172.16.1.1 255.255.255.192 Server Fa0/0 - 172.16.1.2 255.255.255.192 ; 172.16.1.1 Server Fa0/1 - 172.16.1.3 255.255.255.192 ; 172.16.1.2
Triggered it : PT uses 1st port as the default port to forward traffic to the outside network. The 2nd port is only for forwarding traffic within the subnet. Configuring default gateway on 2nd port is insignificant.
How to subnet my network for what all traffic can pass and be filtered?