First off, I have my RPi4 on a static IP set from my router. I have configured No-IP DDNS which is compatible with my ISP's modem/router so it should be updated with the correct public IP, and have changed my SSH port from 22 to another one, let's say 2222, by changing the sshd file sudo nano /etc/ssh/sshd_config. I have forwarded this port 2222 to my RPi4 static IP address, and port checking websites show that my public ip has the port 2222 open (checked locally on my RPi4). Despite all this, when using PuTTY on my Windows laptop connected to my phone's data connection wifi hotspot, which is supposed to simulate an external connection, the connection times out, not a refusal, but a timeout. Can anyone shed light on what might be going on here? FWIW, remote desktop doesn't work either and BOTH SSH and remote desktop work when I am on the same local network using the local IP addresses.