Fix Synology Docker Containers No Internet Access

The Problem

You have started a new container in your Synology NAS using Container Manager, but for some reason it does not have internet access.

The Solution

Fortunately, it is very easy to fix. It is most probably due to your Synology's firewall rules. So, all we have to do is add the docker container's IP ranges to the firewall

Step 1 : Find your docker container's IP range

Open "Container Manager" and go to your container that is having issues. Go to General -> Network

Here, you should be able to see the IP address assigned to your container. Make note of that.

Step 2 : Update firewall rules

Open Control Panel -> Security -> Firewall and Edit rules

This should show all your current firewall rules. Click on Create

• Ports: All
• Source IP: Specific IP -> Select-> Choose Subnet
  • IP Address: Put the IP address from previous step, but replace the last number with 0. For example: 172.18.0.0 in my case. This will be the network address of our docker container
  • And under Subnet mask : 255.255.255.0

• Action: Allow
• Make sure to check Enabled
• Press OK

Very Important!!

This would have created a firewall rule allowing your container's network. However, if you have a deny rule, it most probably is above this rule. So, drag your new firewall rule above the Deny rule. Check the screenshot

That should be it!