[SOLVED] How do I configure apache to return 404 on unconfigured subdomains?

Issue

I am self-hosting a website on a Debian computer with apache, and in my DNS configuration I have set all subdomains of my domain (*.mydomain.com) to go to the IP of my Debian computer. How do I configure apache so that if someone goes to a subdomain that doesn't have a virtual host, I have a separate file for each subdomain, they get a 404 error instead of seeing the content on the root domain? I have tried editing the 000-default.conf file and put the following in it:

<VirtualHost *:80>
        ServerName null
        Redirect 404 /
</VirtualHost>

<VirtualHost *:443>
        ServerName null
        Redirect 404 /
</VirtualHost>

But now when I got to mydomain.com I get the following error:

This site can’t provide a secure connection
mydomain.com sent an invalid response.
ERR_SSL_PROTOCOL_ERROR

Oddly if I go to one of the subdomains that I have configured for mydomain.com it works correctly and I see the page that should be on the subdomain.

Solution

 Your connection is not private

error messages comes from the certificate used which is probably not valid for the domain you're connecting to. Wilcard certificates such as *.mydomain.com are valid for 'third-Level.mydomain.com' but NOT for 'somthing.third-Level.mydomain.com' which requires a wildcard like '*.third-Level.mydomain.com'.

You can get free and valid wildcard certificates from Let's Encrypt (https://letsencrypt.org/)

Answered By - Inc0

Answer Checked By - Willingham (WPSolving Volunteer)