Ok. So based on your updated comment I think you might be closer than you think.
Also yeah I had the same issue with my first hosts, not with node.js getting installed but with opening ports on the firewall.
So if you know for sure that the local server has 5100 open and is listening [ sudo lsof -i:22 ]
If your certs are valid for the site you are hosting, then change https://externalip:5100 to https://yourdomaintothehostedsite:5100
If the cert is valid and the port is open you should (maybe?) connect or get a new error, at least that’s been my experience