I recently setup a basic Ubuntu Server at my home and while at school can't access it because the SSH port (22) has been closed. This lead me open up different ports on my server for SSH so that I could access via an open port at my school. I ended up opening port 21 typically for FTP because I did a network scan and found it was open on the school network. I tested SSH from my home network onto the server using port 21 and was successful but upon attempting it at school I was unsuccessful. My question is why was it unsuccessful? And what can be done to fix it?
I am aware that I shouldn't be trying to circumvent there blocks but I am really curious on why it isn't working.