Can't Login to Admin Website - 403 forbidden

Hi Folks,

we added a new member Server and face a strange issue. The server was installed without any issues and we can access the web management using the IP without any issues.

After that we added some DNS and installed Let’s Encrypt - again without any issues.

We want to run some services on this member using a diffrent tld than used for the DC Master… but using this domain we get an

Failed to load resource: the server responded with a status of 403 (Forbidden)

Using a subdomain same as our master works like a charm…

Any idea where we need to add this alternative domain so that we can also use this for the management or is this a security feature that management websites always need to use the “mail” domain?