@hgeifman- You have to ensure that Bricasti M21 is accessible from your MAC computer, else no software installed on that MAC will be able to connect to it. One way to do that would be to ping M21 from your MAC computer after getting the IP address of M21 from your Router's admin page. You would need to open a Terminal (found under Applications->Utilities folder) window on your MAC and issue the command ping IP Address. If you see a response like
64 bytes from 192.168.X.X: icmp_seq=1 ttl=64 time=0.533 ms (where 192.168.X.X is the IP address) on the Terminal then M21 is visible to your MAC and the problem is most likely with Audirvana...
Alternatively you can install Roon or JRiver software on your MAC and verify whether they are able to connect to M21.
W/o the confirmation that M21 is accessible from your MAC it would be difficult to isolate and troubleshoot the real issue.
Thanks.