Sometimes ISP (Internet Service Providers ) by Ports for communication to block spam and viruses from spreading across the network. CanYouSeeMe.org is an online Open Port Checker Tool that remotely verifies if a port is open or closed and check to see if a server is running or a firewall or ISP is blocking certain ports.
The interface is simple, Your IP address is identified and just enter port number that you want to check.
You can also use http://www.portcheckers.com scan ports or test port forwarding
you can use for port scanner and checker https://www.cmyport.com/