ARC stopped working: 'Poor Connection' & 'Core Unreachable' messages on Three UK Mobile/Cellular (fine on wifi)

Hi there,

Alas, after a long period of stability, over the last few days, I’ve been unable to use ARC on my mobile/cellular connection at all (Three UK).

Roon advises that ‘Roon ARC can securely access your Roon Core’, but this is only true via Wifi for me.

Error messages include:

  • Core Unreachable
  • Poor connection
  • Can’t connect to your core

ARC remains accessible for my wife on Cellular/Mobile (she’s on a different mobile network).

Over the weekend, I was visiting family, and I found that connecting via their local Wifi network also worked fine, too - presumably this points to my cellular mobile provider.

I have a feeling that my Mobile Provider may have made some network changes in recent days, as part of their roll out of ipv6 and this is playing a part.

Anything in the logs indicating what the ARC issue might be when I use my iPhone 12 Mini via the up to date Early Access ARC?

Everything else is working, perfectly! :slight_smile:



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Hi @Greg_Ince,

Have you been experiencing this error in recent weeks and on more recent builds of ARC? We’ve examined diagnostics and seen some connectivity failures, but would like to confirm the current symptoms of this issue.

There are more general reports of Three implementing pooled IP addresses in some sort of dynamic assignment that might be interfering with ARC. Thank you!

Hi @connor - yes, Three did make some changes that resulted in my cellular data no longer supporting Arc.

I’m actually using a workaround which seems to work, but phone battery life is taking a hit ever since - so I’m turning mobile data off when I’m connected to a WiFi network!

The workaround on iOS has been:

Changing the three mobile APN from to 3internet after discovering this was being recommended for similar issues on the the Three support community in relation to VPN/UPNP/IP dependent services.

I’ve also put a parallel workaround in place on my 5G internet hub as my broadband is also from three, too - and I found that being updated also removed my ability to successfully configure ARC.

Roon dedication! :laughing:

Finally, I’ve just switched APN to illustrate and immediately hit the ARC error time stamp approximately 20:15 this end.

I’ve also reinstated the workaround and it re-enabled Arc access after some restarting. - that was done at about 20:19.

Hope that’s helpful.


Thank You!!! Was having issues and I think this solves it for me. :slight_smile:

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Glad to hear that it helped! :+1:

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Got me back in the game too.

Many thanks.

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Great stuff! :+1:

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