Mac drops connection with NAS on library scan

[jdough52]

So, two things up front.

1. I know this is not technically a Plex issue, but the only reliable way of reproducing it every time is related directly to Plex, so I’m just hoping someone else in this community has also come across it.

2. I did search the forums before posted, and I am aware that similar issues have been reported multiple times (here and on reddit), but the few suggested solutions that I found did not help me.

What’s happening:

I very recently switched my home server from an Ubuntu machine to a new M1 Mac Mini (running Big Sur). I migrated Plex Media Server from one machine to the other with no problems at all (library and watched statuses all intact). My media files are on a Synology NAS (DS 719+). They have been there for over 2 years, and I never, not once, had the connection drop under Ubuntu.

Since switching to Mac, the connection to the NAS / shared folder drops frequently. I noticed it first when indexing the migrated libraries for Plex, but it also has since cut out multiple times in the middle of streaming content to a player. When I go into Finder and reestablish the connection manually, it works fine again for while, before it just disconnects randomly again.

Only … it isn’t really completely random: I noticed that the connection regularly drops at the very end of a (manual) library scan. So, I started testing this. I’ve tried:

• SMB and AFP (fully enabled/disabled individually via Synology DSM)
• Fully automatic DHCP, DHCP with manual address, and completely manual IP settings
• LAN and Wifi
• With VPN client turned on and turned (completely) off
• Adding the mapped drives both to startup items and to favorites
• Activating Server Performance Mode on Mac

… all with the same result: Every time I run a library scan, the Mac drops the connection to the NAS and loses the network share, requiring me to manually reconnect.

Now, as I said: I’m 99.9% sure this has nothing to do with Plex as such; it’s probably the specific load put on the connection during a library scan (and, as I said, it has also happened during streaming). I’m also 99.9% sure this is not a Synology problem, because in 2 years of using the DS with Ubuntu, the connection did not drop a single time (using the same router and network). So, it must be an Apple problem.

But if anyone here on the same or a similar setup (PMS on Mac, media on shared network drive) has encountered the same issue in the past and found a way to fix it (that’s not any of the ones listed above), I would be massively appreciative. I would hate (for reasons) to go back to Linux, but obviously this situation is not tenable.

[zenandjuice]

On the Synology NAS, are you running DSM 7 or 6?

I’ve been seeing a LOT of SMB share drops on my Mac Mini M1 (macOS 11.4) and Synology D420+ (DSM 7) recently. Whenever I start to do some major file activity, the volume just drops.

I have Plex running directly on the NAS, so it’s not a Plex issue.

[jdough52]

Because I hate it when other people leave their topics just dangle, even after they found a solution, allow me to update this briefly – especially because the “solution” here was ridiculously obscure:

In a nutshell, all of my recent problems since the migration to a Mac server came down to one evidently corrupted folder on my NAS.

I stumbled upon this by accident, when copying all of my data to an external drive in order to test moving all media files to a new location to fix the problem described here. Every time I tried to access this folder (one season of one show) in Finder, Finder would crash. Like, completely. Spinning wheel of death, unable to restart either Finder or the Mac, needed to hard reboot. Every time (beforehand) when I selected multiple (or all) folders to copy with this folder included, the entire network share would eject. I couldn’t even delete the folder, as that also resulted in Finder crashing.

So, once I was sure (through painstaking – and painful – manual trial and error) that no other folders on my NAS were having the same effect, I simply copied all data except that one folder to the external drive, then completely wiped and factory reset the NAS and the drives in it. Afterwards, I copied all the data back, minus that one folder.

Lo and behold: Everything works now! Not only does Plex now find and add all shows again (before it must simply have quit whenever it hit the corrupted folder part of the way through the library scan), I’ve also had zero disconnections of the network share following library scans.

I literally have no idea whatsoever how one corrupted folder (or even one corrupted file in one folder), especially one stored on a NAS (i.e. not even on the server itself), can cause issues on this scale. But, empirically, it somehow did.

I’ve now set up a new data scrubbing schedule on my NAS and hope this will prevent anything like this recurring in the future. And while this is probably a one-in-a-million edge case, I still wanted to leave this here for anyone experiencing similar symptoms. Make sure you check the integrity of your files!

[jdough52]

@zenandjuice I was still running DSM 6 before. After the factory it auto-upgraded to DSM 7. Not sure why it didn’t do that before, or if this also helped solve the issue (although that would sort of run counter to what you found online, I guess).