Hi,
there shouldn't be problem in using ZeroG driver in MQX 3.6 . The MQX enet driver API is still the same as it was in the time ZeroG was released.
You can check change log of the MQX 3.6 (in the Release Notes) and figure out if the features/bugfixes are relevant for your platform and your application. If you decide to switch to 3.6 then it is better to wait 2-3 weeks. In that time should be MQX 3.6.1 released - this version brings several bug fixes.
Regards,
PetrL