[Solved] Cannot register RHEL 7.5 via subscription-manager

'''EDIT:''' Never mind. Today it works.

Hello folks,

I have some troubles to register a RHEL 7.5 host via subscription-manager. The error message is: "Unable to verify server's identity: ('The read operation timed out',)"

The host is a VirtualBox gues with access to the internet. I can ping subscription.rhsm.redhat.com.

Does anybody know or have an idea what went wrong here and for what reason?

Best regards,
Joerg K.