ajharvey wrote

I recommend you try connecting to the service from another device on your local LAN as a validation test - you can telent to the port from the machine itself, but it is quite possible that firewall rules or filtering on the machine are blocking connections from outside the device.

Yes, good point. I have since tested that and the other machines on my LAN also see the port as open.

Kevin_Z wrote

@calum-b 

 

Hello, what is the current internet IP address? 

 

Please use the computer in the same network to do the tests below and tell us the results.

 

A. Use LAN IP+port to test if the service can be accessed from LAN;

B. Use WAN IP+port on LAN PC to test if the port is opened.

 

Meanwhile, please disable the firewall and anti-virus software on the computer.  

Thanks. I will PM you the current public IP address, but I don't have a static IP from my ISP so it will change from time to time.

For the test results below, I disabled the Sophos anti-virus (required for work) on the target laptop. The macOS firewall was already disabled, and I have no 3rd-party firewall software installed.

A: Using netcat to scan the LAN IP+port from another PC on my LAN, the port is open:

B: Using WAN IP+port from another PC on my LAN, the port is closed.

Bales1181 wrote

@calum-b how did you resolve the Double Nat issue?

@Bales1181 It was best part of a year ago now so I can't remember exactly what I originally did wrong I'm afraid... I just recall that I bridged the wrong connection intially. (My ISP's router is a Huawei 658c, so there were four connections to choose from, as seen here: https://www.rgb.ie/2014/10/29/enable-bridge-mode-in-vodafone-hg658c-router/#post/0).