How did you install the Docker Engine exactly?
What do you get when you run the following command?
curl -vvvv https://registry-1.docker.io
you can check the certificate this way:
openssl s_client -showcerts -connect registry-1.docker.io:443 </dev/null
Please use code blocks as described here: How to format your forum posts
You can also check if you have an antivirus on the host. Recently I found out that the ESET antivirus can replace the original certificates with its own cert and cause issues in command line while web browsers accept it.