I am just conveying information from my experience. When mounting CIFS add the follow in to /etc/fstab
//server/ share/ /media/ share cifs credentials=/etc/cifspw,rw,forceuid,guest,mand,file_mode=0770,dir_mode=0770,uid=1001,gid=1001 0 0
where uid & gid is the id of the user syncthing is running under. With just gid alone (no uid) file timestamp information was not passed.
/etc/cifspw has the format
username= user password=pass
syncthing rox, Chris