I have found that if SQL is not installed with the default instance name (MSSQLServer), the installer will time out connecting to the database.
In order to resolve this issue, you can enter in the database field on the installer window, use one of the following formats:
In order to find out the sql instance name:
open Microsoft SQL Server Management Studio
connect to the datatabase
choose "new query"
Enter "Select @@servicename" with out the quotes around it
Press the Red exclamation point for execute
Results displayed are the instance name.
For more assistance, please submit a support ticket at https://support.ipconfigure.com