Arc fail to connect (Comcast/Xfinity w/ Asus Mesh System)

Roon Core Machine

ASUs Zenbook Core I-7
Windows 11
Intel wi-fi 6 Ax201

Networking Gear & Setup Details

ASUS AiMesh system with RT AC 5300 is the primary with RP-AC1900 and RT- AC88u
Xfinity Internet

Connected Audio Devices

Cambridge CXN

Description of Issue

Here is the error message:
“connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“24.5.x.x”,“router_external_ip”:“”},
“status”: MultipleNatFound
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“”,“found_upnp”:true}

Folks this is way more complicated than most of us can resolve on our own. If you put something like this out there you need to make sure it works for most users.


The message says that you have a multiple NAT, i.e., more than one router, which is why things aren’t working for you.

Have you read the support documentation?

Incidentally, Roon ARC is working for the vast majority of users.

Hi @Richard_Gilbert1,

Please accept our apologies for the long wait time while the team worked diligently through the queue of ARC-related issues to reach your post.

The diagnostics you initially shared suggest you might have accidentally hardwired your gateway (Xfinity modem/router combination) between the two routers in your setup. There are multiple LAN and WAN ports on the Xfinity gateway, so I’d first verify the ethernet connections.

It’s been the experience for the majority of Comcast users with ARC that there is no carrier-grade NAT blocking port forwarding, so we can assume the issue here is both 1) in your LAN and 2) resolvable.

Once we’ve clarified the LAN architecture, we can pin down if there’s still a second layer of network address translation in your local network from both routers.

We’ll be watching for your response. Thank you again for your patience.