SSRS issue : The specified network name is no longer available

I'm experiencing an error with SSRS reports executed that take over 1 minute to return data. This is a sporadic error i.e. sometimes the reports fail but sometimes they run. This is only for manually executed reports, subscriptions work fine.

System.Runtime.InteropServices.COMException: The specified network name is no longer available. (Exception from HRESULT: 0x80070040)

This is pointing me to Networking issues obviously.

We do have a separate box providing traffic management features and HTTPS - the actual SSRS box is running HTTP.

I wonder if anyone has seen this error?

Try the following setting in the report -> Properties -> Execution:

If it doesn't help try to increase to 10000 and see if it makes any change