Fix for “Failed to connect to the target server.” error notice within Data Replicator 3

If during first time setup you have enabled the DSM 4.3 firewall on your Synology Diskstation then connecting Windows services (e.g. Data Replicator 3, Cloud Backup, Install Assistant, etc.) requires you to open those ports so that the two can communicate, this is why likely why you’ve run into the famous “Failed to connect to the target server. Check the network or server setting” error message when setting up Data Replicator 3. Here’s the fix:

  1. Connect to the Administration of your Synology Diskstation as an Administrator group user (e.g. admin)
  2. Open Control Panel > Firewall and QOS within the Network Services group
  3. Within the Allow / Deny tab ensure that the entry starting with “Synology Assistant, etc.” is enabled with Protocol set to All, Source IP set to All and Action Enabled
  4. Save changes
  5. Connect to your DiskStation via Data Replicator 3

That’s it!

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Michael Visser

I'm a WordPress Plugin developer, UAV & Raspberry Pi enthusiast and general tinkerer. This domain serves as my development playground for non-WordPress Plugin projects.

One thought on “Fix for “Failed to connect to the target server.” error notice within Data Replicator 3”

  1. Hi Michael, I am having an error message problem with my DS111 connecting via Synology Data Replicator 3. The replicator is one of the startup service, but I get an error message “Failed to connect to the target server.” After a few seconds, the replicator attempts the connection again, and it succeeds, starting the replication process, well first asking if I want to do a full backup…have not quite figure out how to get rid of the dialogue box. I have tried to follow the procedure you suggest in your article, but I think the interface is now much changed and I cannot find the replicator among the standard applications that I can enable in the firewall. Any suggestion for getting rid of the error message (and dialogue box) would be most welcome!

    Thanks in advance. Martina

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