Did you just port forward some ports from your router to your Synology NAS and want to test to make sure that they are open? There is a very useful online tool that allows you to find out if your ISP is blocking certain ports. If you have correctly port forwarded the ports you need, and they remain “closed”, the problem could be your ISP (Internet Service Provider).
The open port checker is a tool you can use to check your external IP address and detect open ports on your connection. This tool is useful for finding out if your Synology DDNS port forwarding is set up correctly or if your server applications are being blocked by a firewall. Just click the blue link above to access the online Port Forwarding Tester.
Add the Port Number then click Check. After a few seconds you will be able to see the result for the port you have chosen.
This tool may also be used as a port scanner to scan your network for ports that are commonly forwarded. It is important to note that some ports, such as port 25, are often blocked at the ISP level in an attempt to prevent malicious activity like email spam.
Note: How To Enable HTTPS on DSM 7.
This post was updated on Wednesday / January 5th, 2022 at 12:53 AM