Asus RT-AC66U - Manual (Page 89)

5. Specify a firmware file, then click Upload.
NOTE: This is not a firmware upgrade utility and cannot be used on a
working ASUS Wireless Router. Normal firmware upgrades must be done
through the web interface. Refer to Chapter 4: Advanced Settings for
more details.
5.3 Setting up your printer server
5.3.1 ASUS EZ Printer Sharing
ASUS EZ Printing Sharing utility allows you to connect a USB
printer to your wireless router’s USB port and set up the print
server. This allows your network clients to print and scan files
wirelessly.
NOTE: The print server function is supported on Windows® XP,
Windows® Vista, and Windows® 7.