Help Please, Quick question on LetsEncrypt and HTTPS

[coffee412]

Hello,
I am going to setup https for some remote management software. Here is my layout so far:

Internal network domain is 'athome.net'
Internet <-----> Firewall server <--------> Daily driver (LM, max.athome.net), VM running on it (test.athome.net)

1. I have a reg. domain name (lets say mycompany.info) and have setup DDNS pointing to my firewall server.
2. I will be opening and forwarding the necessary ports to test.athome.net for my remote management software.

In order to use 'LetsEncrypt' for https with FQDN of 'mycompany.info' do I have to change the hostname/domain of test.athome.net to match that of mycompany.info ?

I am just learning DDNS and https as I never needed them before. I really do not want to use a self-signed cert. If I have to I will make the necessary changes or just spin up a new VM with the changes.

[msseufert]

In order to use 'LetsEncrypt' for https with FQDN of 'mycompany.info' do I have to change the hostname/domain of test.athome.net to match that of mycompany.info ?

That would be simpler. SSL certs are only valid on the domain that is listed on the cert, otherwise it defeats the purpose of the cert validation. You would also need to connect to the host name listed on the cert or it may also be seen as invalid. For example: If you have abc.123.xyz that points to test.some.tld which resolves to 1.2.3.4; trying to connect to the IP or test.some.tld could throw an error even though they are referring to the exact same machine/host.

[Coggy]

You don't have to change your hostname of the server. It's all done in the webserver configuration.
I've got a public server going, using letsencrypt, and its actual hostname is droplet2. Nothing to do with the domain name the webserver behaves as or the certificates it offers up.