Hi Neil,
I do not know on that side. Maybe. Just make a quick test if you want. But the reverse is not working. While I was implementing the 4.0.x client side DLL, the old 3.x server was returning a TF_FAIL when asking for a lease (or a handle, I cant remember exactly which part of the process was failing). The moment I used the 4.0.x server, all worked fine.
You can certainly make a quick test as it is just a matter of trying one exe or another.
Best regards,Alexandre Leclerc