No, i can't open 127.0.0.1:9003 in my browser.
It has 127.0.0.1:9003 in the bindings.
Apparently the server website is "stopped" (in IIS manager). When i try to start it, it gives me the message "The parameter is incorrect".
When i took the properties of the Sever web site, it had as application pool: <Invalid Application Pool>. I changed this to "DotNetPanel Server Pool".
This problem is solved. I have no idea why it happened, but i think it has something to do with the upgrade of 2.0.5 to 2.1.0 (launched the upgrade of the different parts in the wrong order i think).
Thank you very much for your support.