Issue: When you try to get data from Data Connection, you see the following error:
“The amount of data that was returned by a data connection has exceeded the maximum limit that was configured by the server administrator."

Cause: The default data connection response size is set to 1,500 KB for Form Services. If the response from the data connection size exceeds the default limit the warning will be shown on screen.

Resolution: Ensure you follow the steps below:
  1. Open Central Administration.
  2. Go to General Application Settings > InfoPath Form Services > Configure InfoPath Form Services.
  3. Click on Data Connection Response Size. By default, it is 1,500 kilobytes.
  4. Change the Response Size in kilobytes (increase the number).

- See more at: http://expertsharepoint.blogspot.de/2014/07/the-amount-of-data-that-was-returned-by.html