You may have already been down this route, but does the router have a WPS button, and if so, do you know if your printer also supports WPS pairing? If both do, press the WPS button on the router and then on the router navigate through the menus to select the WPS option - does the printer join the network?
If the printer is on the network, have you gone to System Preferences>Printers & Scanners and clicked on the '+' button to add a printer?
If the printer is on the network but you are having trouble adding it, 'Resetting the printing system' can sometimes help resolve problems. The process will delete all printers listed and they will need to be added again:
Mac OS X: How to reset the printing system - Apple Support