When you follow GitLab Document to install and set by
And you will occur x509 self-signed certificate error.
"It doesn't contain any IP SANs" error is caursed by invalid CN (default used domain name instead of IP).
So we need to modify openssl configuration in GitLab server (not GitLab CI Runner server).
Then re-generate self-signed CA.
Copy the new CA to GitLab CI Runner server.