Hello @connor. This is still happening for me.
Yesterday it happened and I got it working again using the Reset Roon ARC command at the bottom of the Roon ARC options.
This is on two devices, Google Pixel 6 Pro and iPad Air. I’m running Roon ROCK on an Intel NUC 10 Core i7.
Today it has happened again on both devices and it says the Roon Core hasn’t been seen for 1 day.
I’m in the house right now so I’m on the internal network. If I disable Wi-Fi on my phone so that I am on the mobile network instead, it still doesn’t work.
According to Settings / Roon ARC in the Roon app, there is no problem and it should work. And looking at my router under uPnP settings, it shows that port 55000 is being forwarded to the IP address of my Roon ROCK.
In case this is relevant, I was playing with backup and restore yesterday. I created a backup and restored it to make sure that works fine. I wonder if this has something to do with it? Just a long shot.
The reason for suspecting restoring a backup is because at the end of that process, it says to press a button to restart, but then it says it can’t find your Core and you have to select another one. So you select the only Core there is (the same one) and then it’s OK. This seems suspiciously similar to ARC not finding your Core, but if you do a reset then it’s fine.