Solution for "The underlying connection was closed" exception raised when calling web services

In some cases the first call to the webservice works just fine, but if in the following few minutes no new call to the webservice is made, the next call would throw the exception shown above. This problem could be solved by altering the generated proxy class; in the GetWebRequest function the KeepAlive property must be set to false

Open the Reference.cs file and add following code in the webservice proxy class: