Roon ARC sees content but fails to play music due to port forwarding issue (ref#AUS81H)

Support
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Network Setup

· I use a single personal router not provided by my ISP

ARC Status

· ARC is *Not Ready*

Roon Error Code

· None of these are listed. It simply says "TIMEDOUT" or similar.

System or third-party *firewalls *or *antivirus software* can sometimes block RoonServer from reaching ARC.

·
Try adding RoonServer and its associated processes to the whitelist of any firewalls or antivirus software you have installed, including the Windows system firewall, if applicable.
[You can learn more about firewall exceptions with Roon here.](https://help.roonlabs.com/portal/en/kb/articles/firewall)

Has the status in Roon -> Settings -> ARC changed after adding exceptions in your firewalls and antivirus software for Roon?
I don't have any system or third-party firewalls or antivirus software.

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

Roon ARC used to work but now doesn't play music but does see the contents. Says port forwarding issue but the right port is open on the router.

Describe your network setup

VFAST, Linksys Mesh. Nucleus

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Can you post the diagnostic output from Roon settings/ARC page? You should be able to “copy” it on that page and paste it into a post.

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Hey @William_Rowatt,

Thanks for writing in! @bearFNF makes a great point - it would be really helpful if you could share the specific error code you’re seeing in your Roon Settings> Roon Arc page.

With that, a few next troubleshooting steps for you to try:

  • Turn on UPnP on your router and try to run Roon's port forwarding test again.
  • Try to set up manual port forwarding in your router.
    • Make sure the IP/Port matches in any port forwarding rule you create.
  • Double-check to make sure you don't have any VPNs, Firewalls, or other network filtering software blocking Roon.
  • Check if your modem is in Bridge mode.
  • Restart your network hardware and update firmware.

Thank you!

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I had done all those steps. Here is the error code.

{
“ipv6_connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“ipv4_connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“91.aaa.bbb.ccc”,“actual_external_ipv6”:“2a02:ddd:eee:fff:ggg:hhh:iii:jjj”,“router_external_ip”:“null”},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“192.168.1.1”,“found_upnp”:true,“error”:“<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/\” s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/\“>\n<s:Body>\n<s:Fault>\ns:Client\nUPnPError\n\n<UPnPError xmlns="urn:schemas-upnp-org:control-1-0">\n501\nPAL_UPNP_SOAP_E_ACTION_FAILED\n\n\n</s:Fault>\n</s:Body>\n</s:Envelope>\n”},
“multinat_autoconfig”: {“status”:“Failed”,“error”:“Unexpected uPnP Control Response - See Log”}
}

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Hello @William_Rowatt,

Thank you for sharing the diagnostics. The key part is this:

UPnPError 501 – Action Failed

Your router responds to UPnP, but refuses to create the port forwarding rule, which usually means either:

  1. Double NAT (two routers active)
  2. CGNAT from your ISP
  3. The router simply doesn’t support UPnP port mapping properly

Because of this, ARC can’t open the port even if you see it as “open” in the router UI.

What you can do next:

1. Check for double NAT

Make sure only one device is doing routing.

  • If the ISP modem is routing → put your Linksys in Bridge Mode
  • If Linksys is your main router → put the ISP modem in Bridge / Passthrough Mode

Double NAT will always block ARC.

2. If your ISP uses CGNAT

Port forwarding will never work.
Ask your ISP for a public IPv4 address, or use Tailscale.

3. Fastest solution: Use Tailscale

It bypasses all NAT/CGNAT issues and works instantly for ARC:

https://help.roonlabs.com/portal/en/kb/articles/roon-arc-tailscale-setup

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My Linksys is the modem and Mesh router. It only has a tick box for NAT and no mention of double NAT, CGNAT nor Bridge mode, and I have a Nucleus and I just read that Tailscale doesn’t work with it.

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@William_Rowatt

FYI:

Double NAT occurs when two or more routers on a network perform the NAT process, creating two separate private networks. A common scenario is when a user connects their own router to their Internet Service Provider’s (ISP) modem/router.

In other words you have a NAT in your Linksys and the ISP may have a NAT on their end.
So you would need to turn your NAT off (NOT recommended!!) or switch to bridge mode In your Router, which you say it does not have. So you may need to contact your ISP and ask them to turn their NAT off for your connection (which they may not want to do)?

CGNAT, or Carrier-Grade NAT, is a method used by Internet Service Providers (ISPs) to share a single public IP address among multiple customers, helping to conserve the limited pool of IPv4 addresses. Instead of each customer getting a unique public IP, multiple users share one, which can prevent direct incoming connections and cause issues for certain applications like hosting services, some gaming, and voice communication, though it typically doesn’t affect common activities like browsing or streaming.

For CGNAT you would need to contact your ISP and ask them if they can disable it and give you a unique public IP address.

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I would hope my ISP isn’t doing those things… and as I may have mentioned (but in case I didn’t) ARC has worked fine for the year or two I’ve had it, but maybe last used successfully a couple of months ago, but who knows what the ISP has done in that time, but if they have made any substantial changes I would have expected a heads up from them. Maybe the Linksys has installed a new firmware sometime and it’s broken uPnP but I have at least tried the suggestion of disabling that and then re-enabling it, but without any change to symptoms.
In case it isn’t clear in my description, ARC sees my Nucleus, i know this as it shows a recently added ripped CD, but when i press play it just spins and never plays the music, This is surely a weird one?

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I may have got that last bit wrong. This is what happens… if I am on the iPhone in the house and therefore on WiFi then ARC works fine. Not that it needs to of course, but it does, so that shows the app is fundamentally ok. If I turn off WiFi and go on mobile service only then ARC fails. It is showing recent adds/rips presumably because it already knows they are there from the WiFi connection.
I have tried turning off on upnp again and still no change.

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Hello @William_Rowatt

Thank you for the update.

This step, in most cases, would lead to the impossibility of using the service on more than one device. Please do not disable the NAT on your main router.

UPnP would not help in this case, as the port is mostly closed on the ISP side.

In the meantime, you are contacting your ISP, please consider using the Tailscale mentioned earlier.

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I have a Nucleus so I can’t use Tailscale.
I don’t know what to ask the ISP so I can’t do that either.

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Hello @William_Rowatt

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?

Please let us know the outcome of your conversation with the ISP, and we will move forward from there.

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Thank you and I can confirm that I have emailed the ISP and explained my issue, and it seems the CGNAT was the problem. They did not say when they had implemented it, but just said they would disable it for me, and to try again after rebooting my router… which I just did and Roon reports ARC is working, and I have disabled wifi on my phone so that ARC uses the mobile service and bingo… it works.
Many thanks to you and ben and bear for helping me.

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Hello @William_Rowatt ,

Glad to hear that the issue is solved after discussing with your ISP, this is wonderful news. Happy listening!

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