Stop subdomain redirect to homepage

In my Ubuntu server i have two vhosts, where each points the DocumentRoot for the folder and ServerName for the correct domain and sub domain. I have done it with example.com and sub.example.com, changed in my local hosts files and they working as expecte, so confgs files are working as expected.

But when i use my main domain with an wordpress installation and write down in the browser subdomain.mydomain.com it always redirect to the mydomain.com . I think should be something with wordpress, since i cannot reach my subdomain where i have a index.html simple file just to test. (In the future i will put another WordPress instalation just for the sub domain, it´s a marketing campaign)

My htacess file in main domain is pretty straighforward

I have already created my sub domain in DNS Record with A and the correct IP.

Any ideas? I was trying to avoid create a multisite…

Thanks in advance.