nmap fails?

This doesn't make sense: localhost:~ # nmap -sP 192.168.1.* Starting Nmap 7.70 ( https://nmap.org ) at 2021-08-03 20:11 EDT Nmap done: 256 IP addresses (0 hosts up) scanned in 206.30 seconds It should have at least found the Epson printer and the router. I was hoping it would find the old HP printer, so I would know what its IP is. --doug