DNS configuration hosting a multi-site with Google cloud (bitnami)

Hi,

I have set up a wordpress multisite through bitnami on google cloud. I do have trouble finding the proper DNS settings for subdomains though. My A record points to a static ip and resolves well. I have also created a CNAME record with the name *.mydomain.com and the value @. I was hoping this would enable subdomains on my site.

It doesn't work. Neither http://www.mydomain.com nor subdomain.mydomain.com do resolve. If I do create a CNAME record with the name www and the value @ then http://www.mydomain.com does resolve.

It is highly impractical to create a A or CNAME record for every subdomain as I need my users to create their own sites (subdomains) and have them available instantly.

What do I need to do to enable resolution of subdomains with a wildcard record in my DNS settings?

Thank you very much.