Cordova File Transfer

I am trying to use ng-cordova file transfer plugin for file transfer.
When i am using a file of less than 2MB then everything is working fine but if i am using file size more than 2MB then i am getting an error of 502.

i am using another web application to upload more than 2Mb file to the same web service and it is working fine but with ionic app file is not getting uploaded.
please help its urgent