Synology NAS sync via WebDAV with Timeout. (NSURLErrorDomain-1001)

Moin Moin,

I am using my Snology NAS since years together with DEVONthink and sync via WebDAV.

WebDAV is activated only via HTTPS on Port 5006. I have a fixed IP address and use a Reverse Proxy for WebDAV to get access to WebDAV via webdav mydomain com without a special port (Reverse Proxy Source: HTTPS - webdav mydomain com - Port 443 - HSTS activated, Target: HTTPS - localhost - Port 5006). I never had issues with this type of configuration and name resolution works really well. Also I do have a valid security certificate for webdav mydomain com, which is correctly assigned, hence no certificate issues do exist.

Since a while I have issues with the sync via WebDAV and the connection ist not stable. Sometimes the connection cannot be established, sometimes the connection is there, but after a while I got errors during the sync process within the DEVONthink protocol: “Timeout. (NSURLErrorDomain-1001)”.

I did some research online, but did not found a solution. Some people mentioned to deactivate CalDAV on Synology to avoid WebDAV issues. CalDAV cannot be configured within WebDAV server on Synology anymore, as they moved all function to a dedicated package, called Synology Calendar. This package is not installed on my NAS.

May be someone had the same experience and knows a solution?

Thanks a lot!

Welcome @mse78

  • Have you rebooted the NAS recently?
    • If not, I’d start there.
  • Have you recently updated the Synology or Disk Station Manager?

Can you connect to your NAS from you local network, i.e. by connecting directly to :5006 in finder/connect to server?

I’m not sure that I understand what you need this webdav mydomain com stuff for. If I understand you correctly, you’re connecting to and this is forwarding you to In a first step, I’d suggest to use a direct connection from the outside (i.e. not your local network) to your NAS on port 5006 (for this, you’ll have to forward this port in your router to your NAS).

Since the error is about a timeout, you should make sure that you can reach your NAS

  • locally (as described before)
  • remotely
    by using ping, traceroute and nc on the appropriate ports.

Not me, certainly. But then I go for a much simpler solution, too: Connect to the Synology DynDNS domain on port 5006. If that fails (as it did today), open a VPN tunnel into my home network and connect directly to the NAS in this local network.

I have a similar setup, but no reverse proxy (I port forward 5006).

A timeout probably means that it was unable to make a connection to If there were a problem communicating between the proxy and the NAS the proxy would send a HTTP 502 back. So that’s where I’d start troubleshooting.

If you are targeting your external IP, your packets need to go through “hairpin NAT” while your client is inside your network. That can sometimes cause problems at the router. For instance, I seem to recall it being broken with eero for a while.

When the problem is happening, can you go to in the browser and does it get there?