That certainly suggests the Sonos devices not being able to reach the share for some reason, which isn’t clear. Since they connect sometimes, but not others, I’m guessing there’s some sort of interruption between the Sonos devices and your Orbi router, but without hard data to look at, it’s merely a guess.
I’d certainly check for the wifi interference between the Sonos devices and your router. I would also be tempted, at least as a test, to wire one Sonos speaker to your Orbi with an Ethernet cable, and start the library scan from that device.
I don’t use an Orbi myself, but I’d be tempted to do a simple network refresh, by powering off all Sonos devices, then reboot the Orbi. Wait a couple of minutes for the Orbi to come up, then power up/ plug in the Sonos devices. If that makes a difference, I’d look in to setting up reserved IP addresses for the Sonos devices, and in fact pretty much anything connected to your network, it is considered ‘good housekeeping’ for a network. And would help keep the disconnects down.
But, if none of that seems to make a difference, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. But don’t post the resulting diagnostic number here, they get sensitive about GDPR.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution. And we, as users, don’t have access to that data.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.
Oh, some added thoughts…
First, don’t think of this happening by your controller app. The controller is merely an interface to what is happening on (all the) Sonos devices. There is one Sonos device (usually the one showing as ‘primary’ when you start the process) that is contacting (via SMB, since the devices run a Linux OS) the device where your files live. If that external device is ‘asleep’ (some computers and NAS devices provide this as a power saving option), then the Sonos speaker attempting to run the process may possibly time out, and fail, so if you have this scheduled, or are running it as a separate command, you need to be sure the location of the files is ‘awake’. I’ve turned off this ‘feature’ on my NAS, so that my Sonos doesn’t ever time out. Honestly, I’m not sure how long it takes to time out, but I’d prefer neither the hassle, nor the potential.
I’m doing a lot of guessing as to your situation. I’m about 90% or higher confidence, but my assumptions are not gospel, nor do I have access to the diagnostic data, which I assume (having never seen one) contains actual error logs. I also assume there is Personal Identifiable Data in those logs, which is why Sonos’ legal team probably doesn’t want them accessible by the public.
Like I said, if you’re not in that ‘this works for most people’ group, submit that diagnostic, and call in. They’ll have the access necessary to see what I can’t.
