I have answered your private support ticket on the same subject. Here is the answer so that it is available to the community if anyone experiences the same problem.
It appears that the Data Link server is correctly installed on your side given the OK response when browsed locally.
When you are accessing http://servername:9090 from the browser it is able to resolve the server name as your machine is probably in the same network as the DataLink server. But when you are trying to create a Data Connector with this servername
, Telerik Platform is not able to resolve it.
To fix the issue, please make sure this servername
is resolvable outside your network or uses directly the publicly - available IP of the server (making sure that this IP is reachable from outside your network). You may need to contact your system administrators on this subject since a firewall may be blocking this port or to obtain the public address of the server machine.
As for the download of the Authentication Key, we currently have an issue with this button as it is not working when you open the page from Data -> Data Connectors.
However there is a workaround as the button is working when you access the page from by opening the Data tab in your app and follow: Types > Create a Type from a DC > Setup a DC > Download ....:
You can also download the key from a web endpoint as explained here