Gitlab CI push to docker-registry fails
Are you sure that your registry is publicly available?
Checklist:

Check if the domain is reachable and responding the right IP address -- nslookup myregistry
Check if your port is open or not blocked any kind of software (let's say via firewalls or AWS security group) -- telnet myregistry 5050
Check if your registry is not restricted for a particular CIDR of IP
Test your login locally and ensure that there is no problem with it