Connection timed out after 5001 milliseconds

Hi,
I am using the Matomo Connect plugin with Wordpress MU.
My Matomo installation is hosted on a different host than my Wordpress sites. At first everything was working fine. Today I have the error WP-Matomo 1.0.30 could not connect to Matomo using your configuration. The following error occurred while connecting: The connection timed out after 5001 milliseconds
Do you have any idea what the problem is? Can you give me the URL of the API call?
Thank you for your help!