QuickBooks Connection Diagnostic tool is made to correct networking & multi-user errors that might happen while opening a ‘Company File’. There are few pre-requisites before running the tool and a technical expert can guide you properly on this. Visit qbenterprisesupport.com to know this tool and its functionality in detail. For a quick answer you can speak to a ProAdvisor at QuickBooks Enterprise support phone number 1-888-986-7735.