Embedded Report Keeps Asking for Login (Need to Increase Session Time)

Hi All

We are starting to make the switch from Tableau to PBI for our company wallboards. We have embedded a report online and use powershell to open a html file which alternates between displaying a jpg (screenshot of tableau) and iframe (containing the PBI report.)

The report keeps asking for a login every 2/3 hours and I was wondering whther there is a way to increase the session time. We don't wan't to publish the report to the web due to security reason. 

Any help would be much appreciated!