Contents
The Problem
On a quiet evening, I decided to connect to my remote server using SSH, but everything went awry due to the ISP.
Having said that, fellow Earthmate, are you experiencing problems establishing a connection via SSH? You see something like: "ssh: connect to host 'mygorgeoushost.com' port 22: Connection refused"? Keep reading, because my solution might work for your case.
The Solution
# First Attempt
IMPORTANT: Can you connect to your remote server using the browser? For example, in my Lightsail account, under the menu item 'Instances -> Connect,' there is a button:

That allows me to establish a connection with my server.
If not, go to '# Third Attempt'.
If so, please connect to your server and execute the following commands on the remote machine(My apologies to Windows users):
Check if openssh-server
is installed:
dpkg -L openssh-server | grep bin/
It should display the binary; if not, please install it with: sudo apt install -y openssh-server
Check the status of ssh
with:
sudo service ssh status
If it is not currently running, you can start it with:
sudo service ssh start
Verify whether port 22 is blocked by iptables
sudo iptables -L
You should observe something similar to this:

If it's not accepting, run this command:
sudo iptables -A INPUT -p tcp --dport ssh -j ACCEPT
Finally, try to connect with SSH from the local machine (your PC):
ssh -vvv -i path/to/key.pem your_user@your_ip_address
# Second Attempt
If it didn't work, try changing the SSH port number from 22 to 2222 by editing the configuration file, on the remote server:
sudo vim /etc/ssh/sshd_config

Now restart it and check if it is listening on port 2222:
sudo /etc/init.d/ssh restart
sudo netstat -tupan | grep sshd
Remember to add the new rule to your firewall settings. For example, in my Lightsail instance, I created a custom rule for port 2222:

On your local device run the command:
ssh -p 2222 -vvv -i path/to/key.pem your_user@your_ip_address
Now it should work. You welcome :)
Explanation: It's necessary to change the default SSH port number from 22 to 2222 because your Internet Service Provider (ISP) is blocking the port.
# Third Attempt
Change your internet connection until the normal command works on the local device, i.e:
ssh -vvv -i path/to/key.pem your_user@your_ip_address
Keep in mind that if you change two connection and the problem persists, it might be time to explore alternative solutions rather than retrying the same approach.