Network Issue on iMac

Core Machine (Operating system/System info/Roon build number)

Mac OS Big Sur, Roon Core 1.7/Build 667

Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)

Core on Wired Lan, several devices on WLAN, iMac on LAN

Description Of Issue

I’m running Core on a Mac mini Server, connected to wired LAN. Then I have several Devices as iPhone, iPad, BlueOS Server, Synology and an iMac.

When I switch off WLAN on the iMac, he can’t connect to the Core Server. The connection does not work on Ethernet.

Core and iMac and all other devices are in the same subnet 192.168.1.x. Both Connections on the iMac (WLAN or Wired) have also addresses in the same subnet.

I tried with firewall off/on on the iMac and the core server, but nothing changes. The Core Server connects only to the iMac, when I choose WLAN first.

I checked Gateway, DNS and all IP stuff on both systems, it seems strange.

Nothing happens, when I delete Roon und the Library Folders RAATServer and Roon and then reinstall Roon on the iMac.

All Connections from the iMac to any other device on the local LAN works either with WLAN oder wired LAN, except ROON.

Does somebody has any idea

Hi @Rolf_Ziegler,

Can you please provide some more details regarding the LAN setup? What is the model/manufacturer of all your networking gear?

How is the iMac and the Mac Mini connected via LAN, are they both connected to the router directly or through switch(es)?

If you try to disable and re-enable the Ethernet network interface on the iMac, does that help with re-connection?

The type of router is unknown, it’s provided by our national carrier Swisscom.
iMac, Ubiquity Access Point, Mac mini Server with Roon Core and other equipment are on the same switch - HP ProCurve 1410-24G.

The next access point to the iMac is an Ubiquity Unifi UAP-AC-Pro. His IP address is on the same subnet:

I already have disabled an re-enabled the Ethernet Interface on the iMac. Nothings changes.
I played with fixed ip addresses and DHCP on the iMac Ethernet Interface and on the Wireless of the iMac.

I’m using a MacBook - he connects to Roon via Wireless and Ethernet. I checked Switch Port and LAN Cable, using it on the MacBook - the MacBooks connects to Roon.
The problem should be on the iMac.

On the iMac I can ping the Core Server either with LAN Cable or Wireless…

I have to miss something!

Something else weird: if a detach the cable or change the sequence of the connections from Ethernet to WLAN - I can connect to Roon. After that, when I change back to Ethernet - I can control Roon, select and play music on all my audio Zones. When I restart Roon on the iMac - it’s still waiting für Remote Core.

The only problem ist getting the first connection to the Roon Core Server.

Hi @Rolf_Ziegler,

Thanks for those additional details, since everything is connected to the same switch this does sound strange.

Are you by any chance using any VPNs or additional firewall/antivirus programs on the iMac which you don’t have on the other PCs? If you have one active it could be blocking communication on the Ethernet port.


Can you please reproduce the issue and send me a set of your iMac logs by using these instructions? Note, in this case your iMac logs would be more useful than Core logs.

WLAN is deactivated and the Roon client suddenly connects again.

Thank you.

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Hi @Rolf_Ziegler,

Are you able to constantly connect to Roon now after making that change? Can I go ahead and mark this case as solved?

I don’t know why, but it’s working correctly. You can mark the case as solved.

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