My RPi 2 died and was replaced with RPi 3. Disk image of old SD card was deployed on a new card of higher capacity. After inserting that card to my new Raspberry Pi 3, it boot up successfully and accepted a local ssh connection. But when I try to ssh via internet, I get a message "connection refused". Sadly, I replaced the router as well. However, I think the problem is in Pi cause I get this error only when port forwarding points on the Pi. For example, if port 25 forwards packets to 192.168.1.25 (ip of Pi), then ssh pi@ -p 25 causes "connection refused" message, the same command with any other port causes nothing. And ssh firstname.lastname@example.org successfully connects me to the Pi. Port forwarding is set up correctly cause MPoD client successfully connects to my Pi via internet as well as my own iOS app using websockets. Firewall and all security stuff is turned off on the router.
If you connect to your Raspberry without naming the port to be used it normally uses port 22. You're using that to connect to it locally, right?
That means your Raspberry accepts connections over port 22. However, if you add -p 25 it will try port 25 but it seems that it's not configured to use that one.
You should take a look into your ssh configuration to see which port is activated and you should look into the port forwarding settings on your router as it might forward it to the wrong port. If you have your router forward port 25 to your Raspberry for ssh it won't work if ssh isn't configured to use port 25. You should either change your configuration to use port 25 or you should forward port 22 to your Raspberry.
Btw, your command
ssh pi@ -p 25
is not going to work as you don't have an IP or hostname specified. But I'm sure you noticed that too :)
Hope this helps.