TL;DR – I have no idea why this is happening as frequently as it is, what’s causing it, or how to stop it. So I’m using AFP for the moment.
I run a Plex server on my Mac mini 2018 running macOS Catalina 10.15.6. I have all of my media stored on a QNAP TS-831X NAS running QTS 126.96.36.1990 with volumes connected to macOS over SMB. This has worked reasonably well with Catalina for the last year (?) or so, but with the latest Catalina update I’ve had frequent (as in every few hours) disconnections from the shares. I’ve tried a variety of fixes, and thought I’d document them here. None of them really worked, so what I’m hoping is that someone with solid macOS chops will be able to tell me what I’m doing wrong.
QNAP and SMB
I made sure I was running the latest QNAP firmware version. I noticed in the latest release notes for 188.8.131.521 that it fixed a problem where “[u]sers could not mount NAS shared folders and external storage devices at the same time on macOS via SMB”. This wasn’t quite the issue I was experiencing, but I was nonetheless hopeful. This was not the case. This thread talked about SMB support levels. I was running my shares with support for SMB 2.1 through 3.0. I’ve since changed that to 3.0 only. No dice.
This guy on this thread thinks he’s nailed it. He may have, but not for me. I’ve included some of the text for reference below.
Performance mode changes the system parameters of your Mac. These changes take better advantage of your hardware for demanding server applications. A Mac that needs to run high-performance services can turn on performance mode to dedicate additional system resources for server applications.
1 – First check to see if server performance mode is enabled on your machine using this Terminal command. You should see the command return serverperfmode=1 if it is enabled.
2 – If you do not see serverperfmode=1 returned, enter this following line of code to enable it. (I recommend rebooting your system afterwards)
I’ve also tried changing the power settings on the Mac mini, and disabled power nap. No luck there either. I’ve also tried using the FQDN of the NAS as opposed to the short name of the device when I map the drives. Nope, nothing.
My QNAP still supports Apple File Protocol, and it supports multiple protocols for the same share. So I turned on AFP and mapped the drives that way. I’m pleased to say that I haven’t had the shares disconnect since (and have thus had a much smoother Plex experience), but I’m sad to say that this is the only solution I have to offer for the moment. And if your storage device doesn’t support AFP? Sod knows. I haven’t tried doing it via NFS, but I’ve heard reports that NFS was its own special bin fire in recent versions of Catalina. It’s an underwhelming situation, and maybe one day I’ll happen across the solution. And I can share it here and we can all do a happy dance.