NAS Access in Catalina issues

Synology NAS 6.2.2 update 4 and Mac Catalina 10.15.3. Time Machine fails, every single time since I have updated with Back Up Disk Not Available, Try backing up again when "nas_name" is available, yet I have it mapped and visible on my desktop. I can access the files, folders, etc. I have cleared the keychain, cleared the cache, connected via afp smb both by name and by ip, turned off SMB and then AFP. Nothing seems to work. So I purchase an WD network backup drive, guess what? Same Error. Same exact problem. I don't get it. Interestingly my MacBook Time Machine will back up fine to the same network drives! Doesn't make sense. I have posted about this on Synology, tried ever suggestion in this thread and that one. At a completed loss.

After my last post, I was sitting in bed thinking about the differences between my MacBook and iMac. Similar year, same software, same NAS - in fact two different NAS's, both work on the MacBook but on the iMac. Same network, router, etc. However, they do connect differently. Wireless MacBook vs ethernet on iMac. On the iMac, I deleted all my NAS keys in the keychain, cleared the server connections, disconnected the NAS and deleted the server in Time Machine, then rebooted everything. Still connected to ethernet, connected to the NAS, add the drive to TM, started a backup and... TM on the iMac failed as usual with "backup disk unavailable". I repeated the same process BUT pulled the cat5 on the iMac before rebooting. Time Machine started backing up, first time since November or whenever Catalina came out. Crazy. I am using a Netgear Nighthawk X6 8000 as my main router and various other Netgear routers in my home network. The iMac and NAS are plugged directly into the same switch, however the WIFI I connected to with the iMac is off a different smaller router, but still plugged into the same switch. I have no doubt this is a Mac OS issue, since my backup worked fine for years until Catalina - however I now believe it has something to do with how Catalina looks at the physical network interface. Nothing worked for me, I have tried every single option over the past several months listed on this board and Synology. I have SMB 3 and 2 large along with AFP enabled currently. I will disconnect some of the routers in my network and see if that makes a difference. Hope this helps someone.

Came to update my post. Since last time it got worse.

Although I said that killing Finder (Force Quit) made the NAS connection work again, it doesn't always. Recently killing and restarting Finder, even rebooting the Macbook pro multiple times, won't work. Difficulty opening the NAS from Finder, can't find folders and when I do, I lose connection during file transfer.

I go to Finder, click on the name of the NAS in Finder, as soon as I try to enter a folder, I get the "not found" error. Same if going through "[Computer name]" > Network. I think even AFP connections don't work. Also can't connect with Go > Connect to Server with IP address (smb://192.168..........) After multiple tries, I managed to connect to the folder, started transferring a 2-3Gb file, then connection drops in the middle. Had to retry many times.

Strangely, TimeMachine seems to work fine. It is using smb.

For reference I'm using QNAP TS-231P, latest firmware (4.4.1.1216)

Hi Guys,

a long time ago already I pointed to my observation, that me - using a german AVM FRITZT!BOX as DHCP and local DNS - do not have the issue.

there are some changes in Finder and Preview. and propbably the way, BROADCASTS have change.

this change might point to some Routers handling this STILL OK, some not.

whe you can exchange / switch your machines to use the router working and then report success / failure, pls.

I upgraded to 10.15.4 today and what was somewhat stable in 10.15.3 where I would only have to reboot every few weeks, now with 10.15.4 I cannot make any Time Machine Backups to my Synology DS918+ and receive an error 45. I have even tried removing and recreating my Time Machine backup, and I cannot even create a new initial backup. I really hope this is fixed soon. It's been a problem for months, and now I can't make a backup at all.

Since originally posting what I did a good month or so ago I have still had no issues at all. Everything working fine including recently upgrading to the latest. If you want to look at what I did have a check back through this post for my additions.

You mean the dns flush ? Did not help.

I went and read every forum entry again and the one thing I haven't tried in restricting the SMB protocol versions that area used to the most recent only. Will try that now.

I just tried something and browsing with Finder worked. I'll have to report back later. The issue could be with NAS login credentials and possibly some conflict (just have to try hypotheses here since we have no feedback from Apple) .

I changed the credentials with which I connect to the NAS. I normally access the NAS with my personal NAS account (not admin), which is the exact same name as my Mac one (NAS username is Firstname Lastname, Mac is Firstname Lastname). Perhaps this somehow creates a conflict, I don't know. So I tried accessing the NAS with a different username (the admin one). Access was fine. Transferred a 3-4Gb file, no interruption.

My TimeMachine has always worked fine, and that is under a completely different NAS credentials dedicated to TimeMachine and a different shared folder mapping.

Do any of you with the issue use DIFFERENT usernames than your Mac one? Or use different usernames for different folders?

@tomfrombamford, I tried all the steps but alas the issue is still here.

Strangely enough, after I had removed the credentials from the Keychain, Finder was nonetheless able to reconnect to the drive, as if it still had a copy in memory of the credentials. It even stored the credentials back into the Keychain. It took a reboot to solve that ghost credential issue.

I have this problem too. My hardware includes a Synology DS1819+ and a LaCie 2big NAS, both with latest patches. My macOS is patched as well to the latest supplemental update of macOS 10.15.4. After a while, I will eventually experience loss of connection to both NAS.

Here are my observations: I can use an alternative to Finder, Path Finder to be specific, to mount, unmount and access both NAS even after Finder has given up. I can access the mounted shares from the Terminal. And, if I enter the path to a mounted share with Cmd-Shift-G in Finder, I can access the share too, while accessing the very same share through the sidebar server location > share crashes Finder.

My conclusion: It seems to be an OSI layer 6 or most likely a layer 7 problem in macOS. That is, restarting, changing protocols AFP/SMB, clearing caches etc. will only provide a temporary relief.

Hello,

I tried various method mentionned here, but none works... :-(((

These ones mentionned as "working method" are not successful for me: https://www.techarp.com/software/macos-catalina-nas-failure/ or https://apple.stackexchange.com/questions/362739/what-causes-some-network-drives-using-smb-no-longer-connect-to-macos-catalina 

 https://mariushosting.com/connection-problem-between-synology-nas-and-macos-catalina/ >> works a bit better (for an afternoon) and then it stops working...

Anyone with a solution or idea or test to be done ? Few users are concerned or everybody ?

Thanks for your help, I am desesperate...

Fly_PetitPrince

The issue has stopped occurring for the past week whereas before it was constant “folder doesn’t exist” and interrupted transfers. I’m sorry to say I have no idea why, I didn’t change any settings. I’m on 10.15.4 but did have issues with that version before. I’m connected mainly through SMB. TimeMachine has always worked and still does. I’m browsing from Finder by the NAS name, not IP. I’ve also mounted separate shared folders.

The issue probably will reoccur, I’ll share.

Feel free to ask questions on my setup to compare with yours.

Not sure, if this resolves your problem, but I actually managed to resolve the NAS time machine backup problem and the connection problems for my time capsule in Finer. In the Time capsule settings, the iPv6 connection sharing had to be disabled for internet (advanced options). And it does not matter whether any smb or afp file sharing is enabled on the computer or not. I do not know what changed in Catalina (or perhaps on my providers iPv6 protocol side, but it started after upgrading), but remote backups over Wifi on time machine work again, and also the finder properly connecting to the time capsule drive. So it is not a firmware problem, as an Apple support person indicated, and I do not need to go back to Mojave.

Just wanted to let you know, as quite some other users seems to have the same problem after upgrading.

Dear Mahallens,

On my side, my Synology is not setup to access internet, therefore I do not see how I could disable IPv6, I tried to search, but without success and I am still with my problem on my side...

:-(((

Fly_PetitPrince

The issue just resurfaced by itself, without me changing any settings. Can’t connect to the NAS by clicking on its name in Finder. On top of that some mapped drives generate some pop-up errors saying they have been disconnected. Backups I make of my iOS devices through a third party app seem to disconnect and fail (something else that only happens since Catalina).

Strangely Time Machine still appears to work. Never got an error there and it appears to complete the backup hourly.