I posted this to a previously reply. It maybe of use to others.
My synctoy always hung. The usual profile of files - large, many, etc..
After hours of trying everything i discovered that it was todo with file names. Special Characters and in some combinations, spaces, it had problems with.
My work around was to focus on the directories where it fails, simplify the file names in that folder and then run synctoy again. once you find out what the issues are with your naming structure you can then do a mass search and replace.
i found that it had nothing todo with file size, number of files, traffic speed, NAS connectivity or andwidth.
Thank you for sharing your work around to this issue. To help us underdstand the root cause of the problem, can you share the kind of special characters in the files? (ie. filename language, language character set, encoding), if you can copy/paste a sample list of the file names that were causing this trouble that would really help.
In addition, what is your operating system's locale (language).
ThanksMaria del Mar Alvarez Rohena
Microsoft Sync Framework