Hi @soyka0120 ---- Thank you for the report and sharing this observation with us.
Just to make sure you and I are on the same page here 
based on your feedback with the ST connected to your switch the MacBook will not connect but your audio zones are available. If you connect the ST to your router the audio devices are unavailable. Is the MacBook able to to connect when the ST is connected to the router?
I know we had looked into a similar behavior previously in this thread and as such have a few more questions:
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Since noticing this latest behavior have you again confirmed the IP address being assigned to the MacBook? If the MacBook cannot reach the ST via finder my assumption is that the IP is not in the same range as the ST. Please confirm.
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Besides the mentioned switch (LUXUL AGS 1016) are there ANY other networking devices in play? Kindly describe in detail your network configuration/topology.
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Being as we mounted the ST to the switch last time and the issue returned may I kindly ask you to verify what the experience is like with the switch temporarily removed from the chain of communication.
-Eric