Bin Server Question

If we are moving from Fusion 7.0.1 to Fusion 7.7.0 should our "old" bin server still work (7.0.1)? Or do we need to update the bin server to 7.7.0?
I just ask because fusion 7.0.1 can still access bin server, but Fusion 7.7.0 gets an <Access Denied> response with the same settings.
I just ask because fusion 7.0.1 can still access bin server, but Fusion 7.7.0 gets an <Access Denied> response with the same settings.