In order for Synology Assistant to find your Synology NAS on your Windows computer¹, certain ports on your computer and Synology NAS must be accessible. This tutorial explains how to adjust your DSM and Windows firewall settings to allow access through firewall.

On your Synology NAS

Follow the instructions in the respective Help articles for DSM 7.x or DSM 6.x to configure firewall rules. When you create an allow rule in Control Panel > Security > Firewall > Firewall Profile > Edit Rules > Create, do the following:

• Under Ports > Select from a list of built-in applications > Select, make sure Synology Assistant, Network Backup is ticked.
  
• Under Source IP, make sure you have included the IP of the computer running Synology Assistant.

On your Windows computer

If you are launching Synology Assistant for the first time

1. A Windows Security Alert will pop up when you launch Synology Assistant.
   
2. Select the type of network that your computer is connecting to and click Allow access. If you are unsure which one is applicable to you, select both.

Doing this allows the traffic of Synology Assistant to pass through your Windows firewall when your computer connects to the selected network.

If you have ever launched Synology Assistant but did not allow access through firewall

1. Press Windows Key and type "Windows Defender Firewall".
2. Go to Windows Defender Firewall > Advanced settings.
3. In the Windows Defender Firewall with Advanced Security window, click Inbound Rules in the left pane and find all instances of dsassistant under the Name column in the middle pane.
4. Double-click on any dsassistant instances with a red stop icon .
5. On the General tab, select Allow the connection, click Apply, and click OK to close the window.
   
6. Repeat Steps 4 and 5 until all dsassistant instances have a green check icon before it.

After you make these changes, the traffic of Synology Assistant will be able to pass through your DSM/Windows firewalls. If Synology Assistant still cannot find your Synology NAS, refer to this article for more troubleshooting tips.

• Turn Microsoft Defender Firewall on or off by Microsoft
• Best practices for configuring Windows Defender Firewall by Microsoft
• Risks of allowing apps through Windows Defender Firewall by Microsoft
• For Mac computers: Set firewall access for services and apps by Apple