There are tons of ways to check if the port is open on a remote server. I think I found the fastest one, which is a Powershell one-liner:
For testing purposes you can use the following command:
It should give you no results. This means connection succeeded.
In real life you may encounter the following two outputs in red:
(1) Exception calling “Connect” with “2” argument(s): “A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond xxx.xxx.xxx.xxx:xx”
(2) Exception calling “Connect” with “2” argument(s): “No connection could be made because the target machine actively refused it xxx.xxx.xxx.xxx:xx”
It depends on the endpoint firewall configuration. For the server, which receives too many connection requests, it is more natural to drop connections (1) rather than refuse them (2).