Redirecting of hostname to full qualified domain name with HTTPS fails

Your SSL certificate for HTTPS should have myserver inside it as a alternative name, as it seem a simple ssl error that block the redirect.

If a homemade certificate please be sure to install it into the client store before testing. You can deploy the certificate by GPO if you are into a active directory domain.

If your cert is for https://example.com, the browser will not accept it to access https://example because the names don't match.

Unless you have self-signed certificates accepted in your browser (and those of all your clients), this can't be prevented, and you won't get any public signed certs (e.g. with Let's encrypt or any regular CA) for a hostname without a TLD.