Domain Alias Limmits

Where can I change those limits?

Look in the Administration Options menu for the virtual server in question, and click “Server Owner Limits”. The option you’re after is called “Maximum allowed alias servers”.

Ok, found that.
But isn’t it possible to set the limit in a template, for new servers?

It should be. But I don’t see it either.

Looks like a bug.

Yes, this is a missing feature … but I have just implemented it for inclusion in Virtualmin 3.47.