Jenkins can access gitlab through the extranet IP address, and can use git with ssh key to clone projects from gitlab.

Then I followed the GitLab Branch Source Plugin tutorial and configured it step by step, but when I entered my gitlab server extranet IP address, I was prompted with this,

Invalid GitLab Server URL: https://xxx.xxx.xxx.xxx:9xx8

and when I clicked on the test connection I got the following error.

Failed to validate the account javax.net.ssl.SSLHandshakeException: java.security.cert.CertificateException: No subject alternative names present 

Attached was the show details error report.

What should I do?