I can't ssh my Ubuntu server from outside via WAN. I read some Q&A all around here and I got to know that the firewall setting is locked to 'Medium' that block traffic from WAN to LAN. Then as per some recommendations I have added the server IP into DMZ and used port forwarding. I used canyouseeme.org to check and port 80, 443 are okay, but port 22 can't be seen. Please I really need to make my server reachable via WAN through port 22. Idk why port 22 is treated differently.
@lenhhoxung32Have a search in yescrowd for "port 22" with quotes and read up to see if anyone has solved it. Another option is to change the SSH port number and update the firewall & DMZ for the new SSH port number. This also means that scripts that check for an SSH port will fail.
This post may help:
Especially the last port, which I 1000% agree with the note in the post as Optus support do not know how to support the modems they sell once you get a issue that is not in the scripts....
I would also head on over to whirlpool and do some searches: