I am unable to connect to the data source.

Hi, 

I have thoroughly searched through the community and nothing seems to be working. I am getting the below error on each visual of my report

We reached the data gateway, but the gateway can't access the on-premises data source.
Please try again later or contact support. If you contact support, please provide these details.

I believe it has something to fo with the gateway. I have updated and reconfigured the gateway but still no avail. I am using SQL Server direct query mode. on republishing the source works fine for about 5 minutes and then breaks.

Just to make things more clear I have other reports querying the same data source but for some reason, only 2 of reports are breaking. I have recreated the reports with a different name but it only works only for 5 mins and breaks. 

Please can anyone help me with this.