I don't believe it's a driver issue as we recently updated to Big Sur also without a problem. To set the address as static, you have to log in to your router webpage (easy to google) and set it within there. Also, the printer setup on your Mac needs ...
Is the IP address to the printer dynamically assigned? If so, it probably changed with the power glitch when the router rebooted. To avoid this in the future, set the address to be static in the router configuration page.
FWIW, after I installed the latest drivers/firmware, I couldn't locate the printer at all from the MAC. I forget the option to do this on the MAC, but I knew the IP address of the printer as I had dedicated it on my router. I told the driver to use...
