· My only router was provided by my ISP
· ARC is *Ready*
My Roon Server shows ARC Ready. But my android phone cannot connect even if I use Tailscale. It was working fine through the beginning of March.
Verizon FIOS is my ISP, Roon server is running on a Nucleus One. I use ARC on a Samsung Galaxy 20 and on Android Auto
Hi @Peter_Solomon,
Thank you for your post. Please note that, for now, the Roon Settings → ARC status only refers to the port forwarding configuration, and doesn’t test the Tailscale connection you’ve set up for reaching the phone.
Are you able to login and reach the homepage or settings page in ARC? What do you see under the server connectivity status, if so?
Verizon hasn’t commonly implemented CG-NAT that would block port forwarding, and since you see a “Ready” status in Roon itself, Roon can actually reach the phone without Tailscale. Do you have issues connecting to ARC using cellular data if you disable Tailscale on the phone and on the Nucleus One and just rely on port forwarding? Tailscale sometimes routes traffic through their own relay servers, which can introduce latency.
We’ll watch for your response. Thanks!
So, I’ve disconnected Tailscale at both ends. I’ve turned off wifi on my phone. When at home (with wifi turned off) Roon ARC connects to the cloud and for a hot minute connects to the server. Then the server disconnects and the server connection “progress bar” spins for several minutes and finally reconnects. It then seems to work fine.
However, when not at home, or using android auto - Roon Arc behaves the same except - once it disconnects it is only able to reconnect to the cloud, but not to the server. I get a message something like “check server - port forwarding problem”
In both cases the Server continues to say Roon Arc is ready.
Hey @Peter_Solomon,
Thanks for giving that a try! We were able to review Arc diganositcs around the last few days, and see that the primary error is ERR_NAME_NOT_RESOLVED — the ARC app on your phone cannot resolve the DNS names auth.roonlabs.net and roonservice.roonlabs.net.
This appears to be a DNS failure on the mobile device side, not a port forwarding problem, which is why the server still shows ARC as Ready.
Here’s what to work through:
1. Check your phone’s DNS settings first
Go to Settings → Connections → More connection settings → Private DNS on your Samsung Galaxy. If it’s set to a custom DNS provider (like dns.google or 1.1.1.1), try switching it to “Automatic” or vice versa. A strict/encrypted DNS setting can sometimes block resolution of certain hostnames.
2. Test DNS resolution directly
On your phone, install an app like “DNS Lookup” or use a browser to visit https://auth.roonlabs.net — if that fails to load at all, DNS is definitely the culprit on the device side.
3. Check if this is carrier-specific
Since it works briefly at home on WiFi but fails on cellular, your Verizon mobile data may be applying DNS filtering or network restrictions. Try toggling airplane mode on/off to get a fresh connection, or temporarily try a different network (like a friend’s WiFi) to see if ARC connects stably away from home.
4. The Tailscale angle
Even with Tailscale “disconnected,” sometimes its DNS resolver lingers. On Android, go to Settings → Apps → Tailscale → Force Stop, then also check if Tailscale left a VPN profile active under Settings → Connections → More connection settings → VPN. Remove any residual VPN profile entirely, then reboot your phone before testing.
5. Samsung-specific DNS caching issue
Samsung’s One UI sometimes caches bad DNS results aggressively. Go to Settings → Apps → Roon ARC → Storage → Clear Cache, then reboot. This is worth doing regardless.
6. Router/FIOS DNS as a secondary check
Since your Nucleus is on FIOS and ARC shows Ready, the server-side is fine. But FIOS’s provided router sometimes has “DNS rebind protection” that can interfere. Log into your router at 192.168.1.1 and look for any DNS filtering or security settings, try disabling them temporarily to test.
We’ll be monitoring for your reply, thanks Peter! 
Hi @Peter_Solomon,
We don’t see much activity in ARC diagnostics over the last few days. Have you tried to install the latest build? A clean reinstall will require you to redownload locally-saved track files on the phone, but it will fully restore authentication and caches and give us a clean slate to test connectivity over mobile.
The network errors we’re seeing are between the Android operating system and the ARC framework; the former is reporting no network connectivity. However, these logs are from back when you originally reported this problem, so we’ll need to investigate a more recent occurrence if it’s still happening.
Thank you for your patience. We’ll watch for your reply.
| 11:43 AM (10 minutes ago) | ||
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| to Connor |  |
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I did NOT make any changes on my Android device. Roon ARC just started working again. At first it was sketchy. Not showing album art or Queue Listings. But the last time I checked it was all working fine (I assuming these are famous last words 
).
Now I have a different problem. My Nucleus One server is attached to a new Onkyo TX-RZ50 receiver and a Sony Bravia TV. Sound output is fine, but I can’t display the Now Playing screen on the TV all I get is a DOS like screen directing me to a network address. How can I get the Now Playing screen to display?
Thanks for your help,
Peter
The Nucleus only displays the static screen with it’s IP, it cannot display anything else and never has been able to via it’s HDMI out. You can on a remote setup a Display, like a TV to show a now playing; but, that is over the network not attached directly via HDMI.
See.
Hey @Peter_Solomon,
Glad to hear the ARC issue is solved. @Rugby is correct here, at the present time, the HDMI output is only used for Multichannel audio and displaying the Diagnostics screen only. Please try to set up a compatible display (such as a Chromecast or built-in web browser) for the now playing functionality.