Mixed Authentification: auth by default and anonymus for certain rooms

Hello Community,

i’ve got a problem as follows…
I successfully configured jitsi-server with authentication=internal_hashed so that only one person can open a newly created room

So the direct call to myjisiserver.com works as it should.

Then I have a custom website that opens from there myjisiserver.com using the external_api.js

As I red in the documentaion for the IFrame API there is a section in the variable options named configOverwrite.
When a (internally authorized) person runs the html page I overwrite the configOverwrite values for the dynamically created room as follows:

anonymousdomain: “guest.myjisiserver.com” and
authdomain=“guest.myjisiserver.com

but this doesn’t work stable.

So my question is:
How to accomplish that task ?
Using authentication=internal_hashed by default and
no authentication for certain rooms ??

Thank you in advance