If you are getting “Connecton Failed.” message for “Test Dialogflow Connection” button that means there could be any of these following problems.
- Necessary IAM permission for your google service account is missing
- Wrong setup of Dialogflow API V2
Owner permission for your service account is required.
Please see the below video for creating a google Service Account with owner permission and create a dialogflow agent with this Service Account.
Please see the below video for setup the dialogflow API V2 connection for the newly created agent above.