Roon ARC not connecting outside local network after iOS 18 update (ref#SI2CH8)

Network Setup

· My only router was provided by my ISP

ARC Status

· ARC is *Not Ready*

Roon Error Code

· “natpmp_autoconfig”: {“status”:“NotFound”}, “upnp_autoconfig”: {“status”:“NotFound”} }

Have you successfully located and enabled the UPnP or NAT-PMP settings in your router's web UI?

· I've turned UPnP/ NAT-PMP on and ARC won't connect

Select the Diagnostic Keyword or Text String

· Something else

Don't give up yet.

· I'm stuck. I'd like to create a post to ask Roon Community for help.

Describe the issue

ARC ran without problems until the update to iOS 18. After the update, the status is “Not ready” and ARC only plays in the wifi network. No connection is possible outside the network.

Build 1470 on Mac mini, ARC 1.0.57 Build 306

{“ipv4_connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“95.aaa.bbb.ccc”,“actual_external_ipv6”:“null”,“router_external_ip”:“null”},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“status”:“NotFound”}}

Describe your network setup

ISP O2
FritzBox 7590
Mac mini
CAT7 LanCabel

Hello @Thomas_Schirrmeister ,

After updating to iOS 18, did Private Relay by any change get enabled for your iPhone?

Hello Nori’s,

switching the private delay on and off does nothing. ARC still not ready.

Hi @Thomas_Schirrmeister,

Thank you for your post. I would check on the Mac System Settings under “Privacy & Security” → “Local Network” that Roon has local network access. However, the Mac OS update likely wouldn’t have an effect on the router port forwarding and firewall settings.

The most likely culprit here is your provider, O2, who is in the process of rolling out carrier-grade network address translation (CG-NAT) on their residential tier accounts. CG-NAT blocks port forwarding above your account level. The likely implemented CG-NAT for your account around the same time you updated your iPhone.

To be sure, you could try creating a manual port forwarding rule in your Fritz!Box router settings that points to the port number and IP address listed in Roon Settings → ARC.

A simpler solution is to install Tailscale on the Mac and iPhone. This would bypass your ISP’s implementation entirely. Many users in your position rely on this method instead of port forwarding:

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