When using smbfs there is a limit:
mount -t smbfs -o username=me,password=xxxxxxxx //gatekeeper/foodir /bardir
This only supports files <2 GB
When using samba (eg smbclient) then fies >2 GB are OK.
There are ways to remove the limitation on smbfs, but they are not implemented (and I don't have the skill to resolve this)