@MBOak 

Check the printer network settings to make sure they are not statically set for any IP address for but DHCP. If the printers are set to grab an IP see what IP they are receiving, and try to ping it on a computer. 

The printers should work when connected directly to your computer, if not grab whichever driver you need in order for them to work. Once they work when directly connected to the computer, connect the printers back to the Deco network.

@Tony 

Thanks for your reply.

I ultimately got all 4 printers to work, but feel like it should have been easier.

For the print functions, I re-configured the ports to have the changed IP addresses for the new network, since the Deco router uses 192.168.68.xxx instead of 192.168.1.xxx as the old router did (and, as has been noted elsewhere, there's no way to modify the Deco router to use the old addresses).  I think this was due to using static IP addresses for the printers in the old router (but if the Deco software gave me the same level of control I had for the old router, it would have been much easier).

To get the scan functions to work, I ended up uninstalling & re-installing the Brother software that includes the drivers and utilities.

For both processes, this meant making changes to each of the computers that wanted to use the printer and/or scanner.