Hello,
Thank you for your enquiry to FRITZ! support.
Your FRITZ!Box 7590 AX is to be connected to your Sunrise Connect Box 3 and the answering machine is to be time and day-controlled.
The following instructions show you how to operate the FRITZ!Box on a different router.
https://fritz.com/apps...How to set up the answering machine when operating as a cascaded router, including day and time control, is described here:
https://fritz.com/apps...If you have any further questions or require assistance from our technical support team, please contact us by e-mail at fritzhilft(at)avm(dot)de. Please include the ticket ID #7148595 in your enquiry so that we can allocate your support ticket more quickly.
Kind regards from Berlin
Your FRITZ! team