Hi All
I came across this thread after updating to 10.13.2 to discover the very helpful disabling of FTP by Apple and the issue of being able to scan via FTP to our Canon IR C3525i. I tried the FTP Scanner App, using some of the suggestions above, but just couldn't get to work. After pulling my hair out for a couple of hours, I decided to try SMB. I also tried setting up the connection using the Control Panel on the printer itself and was able to make a connection to the Macs by browsing and, would you believe it, a scan appeared on the Desktop/Scans folder!
I saved this entry in the address book and went into the Printers Web Management page on the Mac to check out what settings it had given it. The Hostname was taken from the Mac's Sharing name in System Preferences, with 2 backslashes before and backslashes used for the path:
Host name - \\DOMENICOS-IMAC\scans
This folder was actually on the Desktop, odd that I didn't have to put the full path in...
Folder path was left empty
Username and password as Mac username and password
On Mac sharing, enabled SMB
Went through and did this for all Macs in office and all worked AOK, apart from the last 2 of course. After some more hair pulling, discovered that if you rename the Mac in Sharing prefs and then amend it on the printer, it goes through!
Thought I would add this to the post in case it helps someone else, might save their hair.