Roon ARC - Multiple NAT error

Roon Core Machine

<!- MacBook Air 2020 i5 8GB →

I’m getting the following error when trying to set up ARC:
“connectivity”: {“status”:“NetworkTimeout”,“status_code”:998,“error”:“”},
“external_ip”: {“actual_external_ip”:“”,“router_external_ip”:“”},
“status”: “status”: MultipleNatFound
“natpmp_autoconfig”: {“server_ip”:“”,“found_natpmp”:true},
“upnp_autoconfig”: {“server_ip”:“”,“found_upnp”:true}

I’ve tried to follow the troubleshooting but no luck so far. I have a Telstra 5G with a 5g Home Modem.

Networking Gear & Setup Details

Connected Audio Devices

Number of Tracks in Library

Description of Issue

Chances are they CGNAT, nothing you can do unless they offer a public IP address purchase option.

Hey @Gerry_McInally,

Thank you for reaching out for assistance with port forwarding / ARC. After reviewing the information you’ve provided, it appears that you may be running multiple NATs in your setup. Please review our help article on the subject, and let me know if you’re able to solve the issue through the steps provided.

If, after going through the above, you still experience issues, please provide the following information:

  1. Who is your internet service provider?
  2. Please list the make and model of your modem and router?
  3. Do you have any additional network hardware, like additional routers or managed switches?
  4. Does your network have any VPNs, proxy servers, or enterprise-grade security?
  5. How is your Roon Core connected to the internet?

You may need to reach out to your ISP to ask about getting a static IP address.


Hi there
My ISP is Telstra in Australia. The modem is simply called their 5G Home modem.
I don’t have any additional internet hardware at all, nor VPNs etc.
My core is currently a MacBook connect wirelessly.

Hey @Gerry_McInally,

Thank you for your patience while we’ve diligently worked to reach every request for support with port forwarding. The diagnostics you’ve provided suggest there is a redundant layer of network address translation preventing port forwarding.

This can either be at the local-network level (commonly as a result of two routers), or at the level of your service provider (in the form of carrier-grade NAT).

If your setup involves an ISP-provided gateway (modem/router combination) and your own third-party router:

  • In the web administration interface of the ISP-provided gateway (modem/router combination), enable Bridge Mode or equivalent, where the ISP-provided gateway does not have DHCP routing enabled.

  • Alternatively, if you have already created a manual port forwarding rule in your 3rd party router, you can add an additional rule to forward the port through the ISP/second router.

If you only have one router in your setup or your modem is already in Bridge mode, please take a look through our list of known router and internet service provider solutions, as other users may have already encountered the same situation: ISPs and Routers: List of Known Solutions and Workarounds

You can reach out directly to your service provider to ask if they support port forwarding; this question will often enough to prompt them to explain whether or not the carrier-grade NAT they’ve implemented can function with ARC.

More specifically, you can pass along the following questions:

  • Have you implemented carrier-grade NAT for my account level?
  • Have you fully implemented IPv6, or do you have IPv4 addresses available?
  • Can I request a static IPv4 address to support port forwarding?
  • Are there any ports you have reserved at the ISP level I should be aware of?


Hi Gerry, after a whole day trying to port forward this, i was able to do port forward the roon core.
Are you using a separate router from your Telstra Modem?
If no - you can check the IP address that’s allocated to your Mac from the “device” settings on the Telstra smart modem then add the IP
If yes - yes, then you’ll need to do the same as above, but add the router’s IP address

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I solved my multiple NAT by:
(my configuration)

  1. modem sagecom (KPN modem 12 in the NL) wired connected to
  2. mesh router ORBI = (fixed) and
  3. ORBI to ROON= (Mac; fixed).

Port forwarding on both modem and router:

  1. port 51234 (or whatever you prefer) to and
  2. port 51234 to
    (thanks to tweakers post, tx Ben (V))
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