I have an 8400 and it works fine with Windows 10 and El Capitan connected via ethernet network. I belive the 6400 won't be any different as long as you download all current drivers and updates via Canon.
If the driver listed is not the right version or operating system, search our driver archive for the correct version. Enter Canon imagePROGRAF W6400 into the search box above and then submit. In the results, choose the best match for your PC and operating system.
You can't use anything over 2 years old on Catalina. CS6 plugins can't work. Luckily, There is a new plug-in. -ipf6400.html?type=drivers&driverdetailid=tcm:14-1924370&os=macos%2010.15%20%28catalina%29&language=en
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