If you have a printer that has the capability to print only 1 strip at a time (like the Primera IP60) then you can tick "Single Strip Compatibility" under the Strip Configuration tab.
Make sure you do have the latest version of the print server in order to see this option.
Latest Windows Print Server App Version: 1.2.2
Latest Mac Print Server App Version: 0.3
Just to note, if your print out does not work the first time with the new update (prints 1 strip in the middle of a 4x6), then please click the small text under the drop down that says "clear selected configuration" and then configure your printer settings again and it should work.