Name resolution for Synology servers sometimes not working

Question

I'm not really sure if this is a Synology issue or a Windows issue.

I'm running all Windows 10 Pro machines on a Windows Server 2012 R2 domain. With somewhat disturbing frequency (let's say 5% of the time), UNC paths to my Synology boxes don't work (as in, trying to browse to \\synology-server\ in Windows Explorer), and I must browse using the direct IP address of the box (like \\192.168.1.10\).

This affects some of my GPOs as I deploy some shared network folders as shortcuts to my users using UNC paths to the Synology boxes. After bringing this up to Synology support, they recommended I always use the IPs for reliability, but I really don't see why UNC paths shouldn't be just as reliable.

FYI, I am running DNS servers from two local Windows Server 2012 R2 boxes (both of which are also DCs), and both those DNS servers are assigned to my client machines via DHCP. Even stranger, when the UNC path is not working in Windows Explorer, I can ping the server name and nslookup the server name with instant responses from my DNS servers.

Any ideas on what I can do to troubleshoot this situation?

Solution

I was having the same problem and it took me a couple of hours to figure out, so thought I'd share it.

Go to your Synology's Control Panel -> Network -> Advanced Settings (under General Tab) : Uncheck 'Reply to ARP Request if the Target IP address...'

Once you hit apply it may take a couple of minutes to reflect and BAAM. Works like a charm!

Hope this helps

Comments

[Stephan]

Search for Strict Name Checking; support.microsoft.com/en-sg/help/3181029/…

[Daniel]

the Synology server is joined to the domain, so it automatically has a DNS entry in the DC. I have performed nslookup while my UNC browse fails, and I get instant response from the DC/DNS Server with the correct IP. It makes no sense. Similarly, I can ping the UNC name and it responds from the correct IP.

[Ryan Babchishin]

@Daniel Yes it does make no sense

[Daniel]

I'm curious to know more about the reason WHY this fixes the problem...

[Daniel]

Is your Synology connected to a domain? I assume not since you said "not running a DC" - just wanted to make sure