Thanks for your response. I’ve spent a lot of time reading and learning and I eventually worked out how to do it. Easy when you know how but days of working it out when you don’t. I bought an SSL certificate from (withheld) for my domain name. I saved my private key and the Root Certificate file (the one with all the random characters) over the ht_host_ras_key and ht_host_ras_key.crt files in the no machine installation. (withheld gives 3 files so it took me a while to what out what needed to go where).
I didn’t need to use OPENSSL tool to create key pairs as the article suggested as withheld provides everything you need to create a certificate. Then you just save your private key and then download the root key later in the next step.
Anyhow it worked. I can now use my subdomain to access to machines through a web browser without it popping up with any security warning. 🙂
Now I just need to work out if I need to port forward to every machine in my router individually or cannot somehow get the gateway/upnp thing to work so I don’t need too. Not sure. It’s only about 20 machines at this point so I might just do them all manually.
Thanks again and I hope my info helps someone.