Enable remote login via going to “Sharing” in preferences, then clicking the “Remote Login” checkbox.
Next, download ngrok
https://ngrok.com/
Once set up, simply write into the command line:
ngrok -proto=tcp 22
Now you can SSH into your computer from the port number specified.
Example: ssh myusername -p PORT_THEY_SPECIFIED
This method bypasses any IP configuration at all, making it bullet proof.
Update: Ngrok2
Ngrok 2 requires authentication. Sign up for an account, authenticate via single command line ngrok authtoken <TOKEN>
Run
ngrok tcp 22
Conntect via SSH via ssh <user>@<HOSTNAME> -p <PORT>