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The MX472 is AirPrint capable so if it is on the same network as your iPhone then it will show up so it is likely that the printer was not connected back to Wi-Fi when you switched to FIOS.
Please make sure the printer is connected to the Wi-Fi network. If you are not sure how to do that, click here: http://canon.ca/support_images/wifits/14s2lw-ww/14s2lw-ww-0010-000/14s2lw-ww-0010-000.html#