Caching server not working (El Capitan server)

I have recently set up a mac server (new mac mini, OS X 10.11.3, server app 5.0.15).

In order to not interrupt the old (active) server, it was first setup with a DHCP address in the 192.168.1.x scope, and caching server was enabled and I could see content was storing on the server.

Afterwards (about a month ago) it was changed to be the active server and the IP was changed to a static in the 10.0.10.x scope.

After that change caching server hasn't worked.

I have tried:

• Restarting the server.
• Turning Caching server off and on.
• Change the location where it should save the content.
• Reset content. (So all the old content was removed).
• Increased size of how much it can contain.
• Made sure that the permission is set to All networks

It works flawless on the other servers I'm running (other places) but not on this one. And the status is green and says everything is fine.

Any suggestions on what to do?

TIA,

Peter