When another computer is using the printer, you should perform the following:
1. Verify the printer’s settings to make sure they don’t permit access from multiple computers.
2. Verify that the computer using the printer at the moment is not Wi-Fi-connected. Change it to a wired connection if it is.
3. Verify the printer’s “default” settings to see if they permit multiple computers to use it.
4. Restart the printer to confirm that it is only being used by one computer.
5. Check the printer’s configuration with the manufacturer if you’re still having problems