QuickBooks error 15215 Server not responding erroroccurs usually due to the interference of a third party application especially firewall or internet security. If you have any antivirus installed on your device, then you can try stopping it temporarily to check if it's creating issues with your QuickBooks. The same you need to do with the Windows default firewall to check if it is blocking QuickBooks desktop payroll from getting connected to the server. In order to fix this issue, you need to add your QuickBooks file to your internet security or firewall so that it won't block it in the future.https://www.quickbooksphonenumber.com/blog/fix-quickbooks-error-15215/