Imac, Wireless Printer Canon MX410 problems after changing router

Bought this new iMac, set it up, hit print for the first time, no USB plugged in and watched as the iMac set everything up nicely and it printed automatically. No software or anything applied that I know of. I switched recently from DSL to cable feed, modem and router hardware was changed. Since then, no wireless printing no matter what I do. Will print with a USB cable. Can I find that initial iMac magic setup again?

Frustrating stuff. Any tips would be greatly appreciated. iMac issue not iPad issue.