Canon LBP7100Cn User Manual page 450

The Firewall settings and so on may be the cause.
Solution
Check the communication settings for the server, clients, and so on.
Cannot Communicate with Server
<Cause> The client computer cannot communicate with the print server.
Solution Perform the described solutions in
Communication Error
<Cause> The USB cable is not connected, or the printer is not turned ON.
Connect the USB cable properly.
Solution 1
"Connecting the Printer and Computer"
Solution 2 Turn the printer ON.
Incompatible Printer
<Cause> The connected printer cannot be used.
Solution Connect to the supported printer.
Incorrect Port
<Cause> The printer is connected to a port which the printer does not support.
Check the port.
"Basic Operations/Various Information for Windows"
When there is no port to use, perform one of the following solutions according to your environment.
When connecting by USB
Solution
When connecting to a network
Network Communication Error
<Cause> The printer and computer are not connected, or the printer is not turned ON.
Connect the printer and computer to the network properly.
Solution 1
"Connecting the Printer and Computer"
Solution 2 Turn the printer ON.
Check the Printed Output
Install the printer driver again.
"Uninstalling the Printer
"Installing the Printer Driver"
Create a port.
"Configuring and Changing the
"The Print Server for Connection Cannot Be
Driver"
Port"
Found."