I use Vuescan Pro and I have a Canon 8800F as well as an HP All-In-One. Vuescan will find both printers, but to find the Canon, I have to select "Manual" and enter the IP address as well as the USB manu/device IDs. My preference would to select either scanner using mDNS protocol.
The HP is stand-alone networked and is found via mDNS. The Canon is USB connected to my server. This server does have mDNS enabled and SAMBA is detected by mdns-scan but the scanner is not.
The firewall is open on the avahi (Bonjour) port 5353.
Other scanner programs find the networked scanner not using mDNS.
What to look at next
The HP is stand-alone networked and is found via mDNS. The Canon is USB connected to my server. This server does have mDNS enabled and SAMBA is detected by mdns-scan but the scanner is not.
The firewall is open on the avahi (Bonjour) port 5353.
Other scanner programs find the networked scanner not using mDNS.
What to look at next