Any chance you’ve defined the new networks as “internal”? (using docker network create --internal on the CLI or internal: true in your docker-compose.yaml).

Because the symptoms you’re describing (no connectivity to stuff outside the new network, including the wider Internet) sound exactly like you did, but didn’t realize what that option does…

It sounds like your issue might be related to how your Docker networks are configured for DNS and internet access. Try these:

1. Check Network Configuration: Ensure your new networks are correctly configured to allow internet access. Docker networks should be able to route traffic to the internet by default unless specified otherwise.

2. DNS Configuration: Since you’re using Pi-hole for DNS, make sure the new networks are properly configured to use Pi-hole as their DNS server.

3. Inspect Network Settings: Compare the settings of old_main with the new networks. Use the following command to inspect the network configuration:

   docker network inspect old_main
   docker network inspect cloudflared
   

   Pay attention to the gateway, subnet, and any custom DNS settings.

4. Check Docker Daemon Configuration: Verify that your daemon.json file is correctly set up to use Pi-hole for DNS. It should look something like this:

   {
     "dns": ["<Pi-hole IP>"]
   }
   

5. Verify Container Configuration: Ensure that your containers are correctly configured to use the new network. This can be specified in your docker-compose files like this:

   version: '3.7'
   services:
     cloudflared:
       image: cloudflare/cloudflared
       networks:
         - cloudflared
   
   networks:
     cloudflared:
       external: true
   

6. Check Firewall Rules: Ensure there are no firewall rules on your host or network equipment that might be blocking traffic from the new networks.

7. Test Connectivity: Run a simple connectivity test from within a container on the new network to check internet access:

   docker run --rm -it --network cloudflared alpine ping -c 4 google.com
   

   If this fails, the issue is likely with network configuration rather than the containers themselves.

8. Docker Network Restart: Sometimes, Docker networks need to be restarted to apply changes correctly. Try removing and recreating the problematic networks:

   docker network rm cloudflared
   docker network create cloudflared
   

If none of the above steps resolve the issue, there might be a deeper configuration problem. At this point, it might be helpful to see the exact configuration of your docker-compose files and the output of the network inspection commands.

Try another dns provider. Put dns: 1.1.1.1 or something in your compose file

What does “old network” and “new network” mean? What are they, LAN setup? Docker setup? Describe them better (netmasks, routing etc.)