If the HP Photosmart is already connected to a computer on a network, for each additional computer you must install the HP Photosmart Software. During installation of a wireless connection, the software will automatically. I recently changed to a new Router with a new name and now my HP C4780 will not connect to the new WiFi. The printer is working fine in making copies and the WiFi is working fine with my Kindle and Cell phone.
This document is for HP Photosmart C4740, C4750, C4780, C4783, C4785, C4788, C4793, C4795, C4798, and C4799 All-in-One printers, and Mac computers.
Hp Photosmart C4780 Wireless Printer
Install the best available Mac print driver and software using Apple Software Update.
note:Where is the download button? The HP drivers install through the Apple Software Update feature on your Mac computer. Your printer is likely supported through Apple Software Update, and you do not need to download anything from a website in order to print, scan, or fax.
Hp Photosmart C4780 Wireless Setup
See the Frequently asked questions in this document for additional information, including how to scan using this driver.