Download the most current "UFR II/UFR LT II Driver" from https://www.canon.at/support/products/imagerunner/imagerunner-advance-c5235i.aspx?type=drivers&language=&os=Linux%20(64-bit), extract it and open a terminal in the extracted folder.
1. Run "sudo ./install.sh
2. Wait until everything is installed and choose y to install a printer, which is also euivalent to "sudo cnsetuputil"
3. Click on add and choose "Canon iR-ADV C5235/C5240 UFRII"
4. Click on lpd and the ip address is: 220.127.116.11. Click register
5. Close the windows if not closed automatically and run "sudo cngplp"
6. Choose the printer and click on properties and choose device settings.
8. Close the properties windows and click on Save.
9. Now, you will be asked to enter ID/PIN and a Username/PIN. Here you can enter anything you want, because this is only valid for the user root. Close the window
10. Now run cngplp without sudo => "cngplp"
12. Change to quality and set the "Colormode" to black and white, such that the standard setting is b/w. You can change it to color if needed.
13. Close the window and click on save and now enter your ID/PIN you got via mail. For the second Username/PIN you can enter anything you want. It is needed for when actually printing the document at the printer. There you have to enter the PIN to start printing.
Please note that there may be a bug, where although choosing Black and white, it is printed as color. Please if you have Linux, tell the admin (email@example.com) to test that if you have the problem.