Mariano is still helping with Troubleshooting the Microsoft Dynamics GP 2013 Web Client – Part 6. Can you say WireShark anyone? Anyone? Bueller?
The Dynamics GP Blogster: Troubleshooting the Microsoft Dynamics GP 2013 Web Client – Part 6
Install, Upgrade & AdminMicrosoft & the GP EcosystemGP 2013
Archived post from 2013. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.