Hi Skipb, welcome to the discussions!
I haven't tried this because I don't use a network printer, so apologies in advance if you have already spent time on it.
If you are using the AirPort Extreme to distribute IP addresses, take a look at the DHCP settings in AirPort Utility.
Open AirPort Utility, click Manual Setup and then click the Internet icon at top of the pane.
Select the DHCP tab and take a look at DHCP Reservations at the bottom of the pane.
If you click the + button, it appears that you can name a client and assign a fixed IP address to that device.
Post back on your findings.