ARC Double Nat on 4G Router

Hi i’m using a 4G router as we live in the countryside and its the best way to get internet. I use a TP link Archer MR600 with 3 deco mesh nodes set up in access point mode - which should avoid double nat. However, i’m still getting this error message? Any advice?



“connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“”,“router_external_ip”:“”},
“status”: “status”: MultipleNatFound
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“”,“found_upnp”:true}

I have a simillar setup, because of a 4/5G mobile modem-router I get from my ISP.

I set up a port forwarding manually on both routers…but no chance to get arc working!?

Any help here?
Thanks, Andreas

Hi @James_Holland1 and @Andreas_Strobl,

Please accept my apologies for the extreme delay, as we’ve worked diligently to reach every ARC user who has reported a port forwarding issue over the last several weeks. There’s no excuse for having tried your patience, and I hope you’ve at least been able to enjoy Roon 2.0 on your home network in the meantime.

Service providers will have implemented a carrier-grade network address translation for your account if you have a 4G router, likely what’s triggering the MultipleNATFound message in diagnostics.

In its current implementation, ARC can’t circumvent carrier-grade NAT. That said, several users in your situation have rather easily bypassed their ISP’s address translation by using one of the unofficial proxy methods listed in our #tinkering section (such as Tailscale or a VPN).

If you’d like to continue to troubleshoot within the realm of port forwarding, it’s certainly possible that your service provider has a pathway for allowing port forwarding or options for changing out routers, IP addresses, etc. free of charge or for little cost. I recommend you pass along the following questions to their service department:

  • 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?

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