OK, thanks @alex_h
This problem has started to become a repeating matter in recent weeks, so a change in experience in general terms for me.
That said, it may not be the first time the matter has arisen, though, as I’ve hit the same situation in the past, and thinking back, it’s often when I’ve had lots of downloads/smart downloads. It sounds like I might want to avoid downloads to the hardware limitations of my iPhone being pegged at 4GB of RAM.
When I have disconnected/reconnected to the server or deleted+rebooted+added the app back in the last few weeks, instead of re-configuring ARC to my liking, including using smart downloads. I’ve experimented with simply accepting the defaults, but the issue still arises nonetheless.
When I do reconnect, because I suspected a large library might be a strain, I’ve have also taken to keeping the phone display from going to sleep, and placing it on charge in order to give ARC enough time to sync for the first time.
Another thought here is that I did migrate my library from an internal drive to an external drive recently - might this have created some library bloat somehow? The timelines of this change and emergence of this issue becoming consistent and repeating each day might intersect here.
As a side note, I am also experiencing the issues others are having relating to Qobuz at the moment, too: playback of particular tracks being impossible, along with a flurry of albums being added again/afresh. I mention this in case there’s a connection, given my experiences of these issues has also emerged in the last week or two, too.
Thanks for the tip re. tailscale. I’ll investigate that, but as this is a change in experience that has emerged very recently, I would also like to establish what’s causing this as its a quite frustrating shift.