When I run nmap -sT -p- it shows port 20323/tcp as open with an unknown service. I have tried (and failed) to block access with a firewall rule.

Can anyone tell me what this is for please?

Mike

I managed to create a firewall rule to block the port. I think it's an internal Draytek admin thing.

I don't have any knowledge of the 2766 but can you ssh/telnet to the device and use netstat (etc.) to see what process is using that port?

Thanks for getting back to me on this. I never did find out what was using that port but I successfully blocked access to it with a firewall rule. I also disabled all unused services and now the only visible port is the one I use for my VPN:

 

I did find something odd. I bought the router from a previous user and although I reset it to factory default before configuring it, the default SSH port number was very large and negative! I have no idea why that should be. I reset it to 22 but have disabled SSH anyway.

Mike