Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
To get started, I need to know what type of computer you are using, a Windows XP, Vista, Windows 7, Windows 8, Windows 10 or a Mac.If its a Mac, please check the OSX version as follows, Click the apple sign at the top left of your screen, then click about this mac. And then where it says version, send that to me as a reply.
Also, what exactly happens when you try to connect the non working unit to your network?
That sounds like either a firmware issue, or a bad wireless card in the printer. Lets try to repair the issue with a firmware update.
First, connect the printer to your computer via a usb cord for a reliable firmware update.
Then, go to this page https://www.usa.canon.com/internet/portal/us/home/support/details/printers/color-laser/mf624cw?tab=drivers#Z7_MQH8HIC0L88RB0AMD0F1Q42K25
On the downloads tab, click firmware.. And then download the firmware updater for windows.
Then, open and run the firmware updater after you download it.. This should connect to the printer, and then flash its internal firmware. Once that is fully complete.. Turn the printer off, then back on.
And then try to connect to the wireless network again.. let me know if you get stuck, or whether or not this works, thank you.
I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.
So the firmware did update?
Question.. Did you try both the automatic and manual wireless setup after the update?
And did we turn the machine off, unplug it, plug it back in and turn it back on after the firmware update?
Can we try an ethernet cord, in order to confirm whether its just the wireless card thats failing, or if its the machine that cant connect to the network period, regardless of the connection method?
Hello again, I never heard back from you. Did you still need help with this issue?
If all went well please make sure to click and submit a 5 star rating to show I assisted you.
Otherwise, please respond so we can work through this issue, or close the question if you no longer need help.
Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.