Problem setting up network printer

I have a 3 Windows computer peer-to-peer network set up on a star configuration, 2x Windows 11 Pro and an old Windows 10 Pro machine that is slowly giving up the ghost.

I have successfully set up a network printer from the old Windows 10 machine and can print to it and scan from it.

I have installed the same printer on the 2 Windows 11 machines, apparently successfully, but can't print from either of them, even though the printer is visible to each machine. The printer is set up on the same TCP/IP settings on each machine.

I have tried turning on Printer Sharing on each machine to no avail.

I don't get any error messages, helpful or otherwise, from either of the W11 machines.

I am stumped - any suggestions gratefully considered.

Thanks in advance.