Question NAS Shared Folder suddenly becomes inaccessible after some time ?

[Yossaris]

Hello everyone,

I couldn't find a thread detailing my exact problem, so I wanted to start my own in hopes of finding a solution.

As written in the title: on my company's Synology NAS Cluster (DS1817 - DSM 7.2.1-69057 Update 6) shared folders suddenly become inaccessible after some time. That period can range from days to hours and I think it depends on the amount of traffic in the subnet in that time. Interestingly enough, the folders can still be accessed from a different subnet that is not at the same physical location as the NAS, while a different subnet at the same location cannot access the folders. After doing a switchover between the passive and the active host, the access is restored.

The relevant parts of the network look something like this:

Subnet 1 - Users from Site 1 where the NAS is physically located
Subnet 2 - Where the NAS' IP-Address is located
Subnet 3 - Users from Site 2, who can still access the NAS, when users from Subnet 1 cannot

This problem is new and probably either started after an unexpected shutdown of the NAS (Blackout with a faulty UPS) or after the DSM Update, but imo it sounds more like a network issue, that I cannot pinpoint.

Does anyone have any experience with this kind of phenomenon? Any suggestion and help would be appreciated.

 

[Ralston18]

What error message(s) are presented when access fails?

Perhaps the unexpected shutdown corrupted files and/or did some physical damage to the NAS.

Did anyone start unplugging and replugging network connections? Swapping ports on the router or switches, etc..?

Another thought is that some of the configuration settings went back to defaults - especially if someone attempted to reset the NAS. Or other network devices. Or trying fixes that involved changing IP addresses and./or subnet masks. All too easy to have some typo wreak havoc.

Check all device IP addresseses (Static and Dynamic) and the corresponding sub-net masks.

I suggest sketching out a full network map showing all devices - not just what is deemed as the relevant partrs.

On the sketch include device names, macs, IP addresses (DHCP or Static) and subnet masks.

Seeing the proverbial "big picture" may help discover what has gone astray.

 

[Yossaris]

Thank you for the quick reply
The only error message that was relayed to me was: "The path is not available.
Cannot access X:\Path\to\folder. The file is currently not available on this computer." (Translated from German)
When put into google, the only solution popping up is that the offline cache is corrupted. But it seems unlikely for that to be the case if it is on every computer in the subnet, or so I assume.

I already went through all the switches and routers in all the subnets looking for some kind of mismatch, but there doesn't appear to be one. I can also access the webUI from everywhere, even when the shared folders are inaccessible.

I thought physical damage or corrupted files to be unlikely, since it works perfectly fine from a different subnet.

For a bigger picture:
Site 1 contains the following Subnets: 1 (for old devices that have not yet been moved to new subnets), 30 (NAS and Servers), 41&46 (User access via Ethernet and WiFi respectively), 42 (Test subnet I setup to check if the folders are still accessible from there)
Site 2 contains basically the same just with different "names" for the subnets (50,61&66)
The 2 Sites are connected by a bridge in a different subnet (155).

All the routing is done by D-Link 3130 Switches, while users are plugged into 1510 and 1210 Switches.

Site 1 users are routed from 41 or 46 to 30 and then gain access to the folders stored in the NAS.

Site 2 users are routed from 61 or 66 to 155 and then to 30.

 

[bill001g]

If it functions from any location it is not likely a issue with the NAS. I will assume the NAS setup is very simple and for example it is only on a single subnet so it sends all communications for other subnets to the router/default gateway.

Your best option is likely to run ping and tracert from various locations. If your router is smart enough you can many times tell it to ping with a source address on different subnets.

Key here is to try to find what is different from the ones that work and the ones the do not. I would also test to other devices on the same subnets. It would be extremely strange if it is only the NAS.

 

[Yossaris]

I will try those approaches as soon as the problem arises again, thank you.
I can't test too extensively every time since the shared folders are needed in the day-to-day business and need to be available as soon as possible, which makes troubleshooting this kind of annoying.