Note: The following information applies to the IS330.x , IS530.x and IS930.x.

The Android operating system is delivered with Random MAC Address. 

What does it means?

The device is not showing a fixed MAC Address anymore for security reasons. The device will create a random MAC Address each time a network is contacted.

How to disable this function?
While first setup or adding a new network you will get the following view
Choose  Advanced options

Open the point Privacy

Select Use device MAC

Your device is working now with a fix MAC address