When the admin requests a QR code, Headwind MDM server tries to download the APK using its URL which is usually pointed to an external IP address. The external IP may be unavailable from the Docker container (especially if your server is behind the NAT).
Here's the possible solution:
1. Determine the internal IP address (not the Docker IP address which usually starts with 172.*!) by using the command
ip addr show
2. Attach to the container by using the command
docker exec -it mdm_hmdm_1 bash
(check the container name by the command 'docker ps')
3. Run the commands
cp /etc/hosts /etc/hosts.backup
echo "x.x.x.x mdm.mycompany.com" >> /etc/hosts
(replace x.x.x.x with the internal IP address and mdm.mycompany.com with your Headwind MDM domain name)
This should resolve the issue.
See also: https://qa.h-mdm.com/1/