Hello tobiaseigen,
yes, I succeeded on an IONOS VPS. I had used the installation procedure and consulted various tutorials for a non-functional discourse. Despite an installation without apparent defects, discourse did not work. Suddenly, I wanted to create another subdomain with the same host and configure the DNS accordingly, and miracle, it works!! 
So, you don’t need much 
just patience.
Thank you for your help, and I think I will still need you for this incredible discourse adventure 
I am closing this topic now that it’s been resolved.
Feel free to start new topics for new questions!
Great! Feel free to recommend it too at Recommended Hosting Providers for Self Hosters.