I had the same problem. Behind a CGNAT. I found a solution and put it in this thread, maybe it can work for you.
OK, that looks interesting. But too much to ingest on my lunch break. I have to come back to that.
I have chatted with Bahnhof and they deny that my IP-adress is a CGNAT-adress.
Well Bahnhof tells me that it’s not a CGNAT provided adress but a public IP4
Well, very strange that you’re seeing a multiple NAT being reported in the error message.
Can you remove any port forwarding rules from the Zyxel that you may have set up, enable UPnP on it, and see what Roon errors you get then?
100.x.x.x is most definitely a CGNAT IP address
CGNAT uses 100.64.0.0/10 (100.64.0.0 >> 100.127.255.255)
{
“connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“xxxx”,“router_external_ip”:null},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“status”:“NotFound”}
}
A few minutes later, back to this:
{
“connectivity”: {“status”:“NetworkError”,“status_code”:504,“error”:“error: Error: ETIMEDOUT, response code: undefined, body: undefined connected? undefined”},
“external_ip”: {“actual_external_ip”:“xx.xx.xx.xx”,“router_external_ip”:“100.124.150.200”},
“status”: “status”: MultipleNatFound
,
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“192.168.1.1”,“found_upnp”:true}
}
OK, I’ve edited out your public IP address from that error message - like your personal email address, that’s not something you should be revealing in a public forum.
That form of error message is shown in the ARC Port Forwarding FAQ, and tells us that we need to do manual port forwarding.
At least the multiple NAT message seems to have gone away - perhaps there was something misconfigured in the modem?
But first, try the steps outlined in the FAQ under “Other Tests” and see if that gives any positive results.
Well I have tried all of that except firmware update. I couldn’t do one when I tried yesterday, but I’ll have another try.
But now it’s back to multiple NAT again. I’ll see what Bahnhof has to say.
I will ask ISP one more time.
Use GRC shields up to see if the port is open.
No point in trying to fix roon if the traffic isn’t even getting to the router or through the port forward.
Ports are filtered according to scan with ipfingerprints, so not open I should think. On hold for ISP support right now. I will ask them (again)
most of the online scanners will say closed even if the port forward is working but roon is not responding.
GRC will say if the port is open even if nothing on the other side responds, it’s a much better indication if port forwarding is working
My Private IP was connected to wrong MAC adress. Now the error message, after Core reboot and toggled UPnP off and on again:
{
“connectivity”: {“status”:“NetworkError”,“status_code”:502,“error”:“error: Error: connect EHOSTUNREACH xx.xx.xx.xx:55002, response code: undefined, body: undefined”},
“external_ip”: {“actual_external_ip”:“xx.xx.xx.xx”,“router_external_ip”:“xx.xx.xx.xx”},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“server_ip”:“192.168.1.1”,“found_upnp”:true}
}
I have confirmed with the ISP, that the IP adress is in fact my Private IP. They say that the manual port forward rule seems OK and that everything should work. Scanning with ipfingerprints and GRC ShieldsUp both report ports are not open.
Any suggestions?
Was your router given to your for free from your ISP? At any rate, you should be able to explain that all you want to do, simply, is to öppna en specifik port i din router för att komma åt en musik-server du har hemma. If they don’t understand that then you can hit me up in a private message and possibly look at this together at some point (over Zoom, for example).
Edit: I didn’t see your latest post. I’m afraid it sounds quite strange but my offer to look at this together still stands, if you’re comfortable with sharing your screen over Zoom etc.
I paid for the router but no-one of the six or seven people I have talked with seems to know anything specific as regards the router. The only thing I haven’t done is to update the routers firmware as I seem to be locked out from doing that, but I have still to confirm that that is the case. I appreciate Your offer to look at it together. Let me just try with Bahnhof one last time. It will have to be tomorrow because I’m kind of busy for the rest of the evening.
Hey @Mikael_Ohlsson,
I wanted to check in on this thread to see if you’re still having issues getting Arc up and running with your network?
Based on the error code you’ve shared, we suggest the following steps:
- Try to manually open the port in your router configuration (here is a step by step based on your router model)
- Make sure the IP/Port matches
- Check for any VPNs or Firewalls
I’ll be on standby for your reply 
Yes, I still have issues. This is the error code currently:
{
“connectivity”: {“status”:“NetworkError”,“status_code”:502,“error”:“error: Error: connect EHOSTUNREACH xx.xx.xx.xx:55002, response code: undefined, body: undefined”},
“external_ip”: {“actual_external_ip”:“79.136.xx.xxx”,“router_external_ip”:null},
“natpmp_autoconfig”: {“status”:“NotFound”},
“upnp_autoconfig”: {“status”:“NotFound”}
}
I have tried to open a port, looks like this:
The IP is the iMac where the Roon Core resides, port number corresponds to the port Roon attempts to listen to.
VPN is turned off but is installed. Firewall on the iMac is turned off. Firewall on the router is turned on, but I have tried with Firewall turned completely off.
UPnP looks like this:
Hey @Mikael_Ohlsson,
Thanks for the info. I’d be curious to know what canyouseeme.org shows when you supply 55002 there.
If it can’t, and you see "Error: I could not see your service on" something from the ISP is blocking the port as this test doesn’t involve forwarding. This site will also reveal what it sees as your public IP. If they don’t match, your ISP may very well be using CGNAT despite them saying you now have a private IP.