Subject Installing Firebird 3.0 alongside Firebird 2.5 and 2.1

I have a testserver currently running both Firebird 2.1 and 2.5.
I need this to support and test various situations with different firebird versions.

Now I would like to install Firebird 3.0 manually as well, so I can have 2.1, 2.5 and 3.0 on the same server.
2.1 listens on port 3050, 2.5 listens on 3060 and I have set 3.0 to listen on 3070.

So far so good.
I then executed the install_service.bat Firebird_3_0
I can now see its running in process manager.

But I'm having problems connecting to the server.
Using Database Workbench to create a server entry I instantly get

connection rejected by remote interface

Sinse security is handled quite differently in Firebird 3.0 I suspect I am missing something here.

Could someone either give me a step-by-step instructions to install Firebird 3.0 manually or point me to places where I can read some about it.

On a difference machine I did run the installer, and I did get Firebird 3.0 up and running. But I need it on this server alongside the other firebird installations

Thank you