I have tried everything on my Fritzbox 5490, I have activated the Port Nucleus Plus as shown in the Fritzbox, it worked surprisingly for a short time, but on the next day I got again the failure message. Have deleted the Port several times and activated new, have deinstalled Roon ARC several times, but no success, unfortunately
Describe your network setup
Innsbruck IBK, fibernet, Fritzbox 5490, Fiberglas, OS Tahoe 26.2
To help us distinguish between a configuration issue and a display bug, could you please clarify one thing?
When you see the failure message, does ARC actually stop playing music?
We are currently tracking a known issue (Error 526) where Roon Settings will report ARC is “Not Ready” even though it is actually working perfectly fine.
Please try this test:
Turn off Wi-Fi on your phone.
Open Roon ARC (using only cellular data).
Try to play music.
If it plays: You can safely ignore the error message in settings for now; it is a display glitch we are working on.
If it does NOT play: Please post a screenshot of your Fritzbox Port Forwarding settings and a screenshot of your Roon Settings > Roon ARC tab so we can check if the port numbers match.
Around the time you posted, there was a cloud service outage that caused an erroneous failure diagnostic to appear in the Settings → ARC pager for some users.
Can you please confirm the following:
Whether you still see this error (paste it here, if so)
Whether you actually have a connection with cellular data in ARC. You can check by turning of WiFi and looking at the settings page in ARC under the cloud/server connection status.