@InTimetec  - could you please check if the port 27017 is accessible from the workspace VPC network? Also, please check with your internal network team for any connectivity issues. 

Per this documented observation - https://community.databricks.com/t5/data-engineering/mongodb-spark-connector-v10-x-read-error-on-dat... you can use DBR 13.3 LTS cluster for compatibility.