Option b (Port 22) seems to the appropriate choice.
Below seem to be some measure you should take to correct this mistake.
- Verify whether Droplet's host IP address seems to be right.
- Verify existing connection supports communication over all the utilized SSH port. Any access points can be able to block port 22 and sometimes customized SSH. For illustration, you could do this by checking different hosts who used the same port, using only a recognized working SSH connection. These could help you identify unless the current problem is not particular to clients' Droplet.
- Authenticate the Droplet configuration settings. Verify that they're not being configured to DROP 's preferred policy, and do not apply the port to require connectivity.
The SSH server also operates on port 22, by default.
Other choices don't apply to the specified scenario. So that the argument presented above will be appropriate.