Hello @bert_brummel,
Thanks for contacting us, I can most definitely take a look over this issue with you. Can you please start by providing more information about the computer that is running Roon Core? Make/Model would be a good first step but for a more comprehensive list of information we wound need to better assist you, that can be found here:
When you say that you have no connection between the iPad air and the DAC/NAS/Zen, can you confirm that you are on the same WiFi network on all of those devices and are not using a “guest” network or anything like that? Do you know if your setup is using static IP addresses or are they being assigned by the Router? I would also reboot all of your devices and the router your have to see if the issue still persists after doing so. Please let me know your findings when possible.
Thanks,
Noris