Failed to request certificate : No virtual host matching main.myhostname.com was found, and a few other questions

Hello,

I currently host several sites on a VPS at Linode without any control panel, just use the command line and nemo to maintain. My sister wants me to set her up a site but she is strictly the gui type, so I thought I would try out Virtualmin and see what it is all about, and set her up a control panel. I don't need mail or anything like that, and I just use the Linode DNS manager to point my domains.

1. Before I add any virtual server to my installation, I wanted to set up ssl for the main server (main.myhostname.com), then add virtual servers. I tried to add a ssl cert through the main webmin configuration, but received the error "Failed to request certificate : No virtual host matching main.myhostname.com was found". I've used the Certbot for my other sites that I host. Would it be better to use that and then change the location of the cert files the webmin config? Or, is it better practice to just add a virtual server called myhostname.com or www.myhostname.com and then use the copy cert to webmin?

2. I don't host any mail server, nor do I have any plans to. Can I get rid of those modules, or are they necessary for Virtualmin to function?

3. Under "Hostname and DNS Client" in the DNS servers list, Virtualmin put 127.0.0.1 and 127.0.0.53. Do I replace them with NS1.LINODE.COM, etc. I can currently get to my site no problem as is. Also, the "Search domains" box lists members.linode.com.

4. Host Addresses - IP Address Enabled? Hostnames 127.0.0.1 Yes localhost ::1 Yes localhost , ip6-localhost , ip6-loopback ff02::1 Yes ip6-allnodes ff02::2 Yes ip6-allrouters Seems to me there there is something missing. The ip of my server maybe? I can navigate to the site no problem, just shows the ubuntu apache page for now.

Thanks for any help in proper configuration of Virtualmin/Webmin. I really don't want to complicate things just to give her a control panel. Thanks again.