I'm pleased to report that the latest version of VueScan (9.7.08), from (removed as per forum guidelines), works with the MF733CDw in all three scanning modes: flatbed, feeder, and duplex feeder. It works equally well when connected by WiFi or by USB...
In Step 2, the Add button remains dim, and MAC Address is "Could not acquire. "The Canon machine prints with no problems. It also scanned until I tried to get VueScan working with it. Now it doesn't scan at all.
For scanning, I'm giving VueScan a try. At this point, it shows my MF733Cdw as a MF731, it doesn't recognize that the device offers duplex scanning, and—worst of all—it doesn't actually scan. I've sent Hamrick (VueScan's developer) a trouble report, ...