Can I use my fios gateway as a switch?

To be concise we had fios gigabit internet. The the ethernet come directly from the ont and goes into my nighthawk x10 router. From the router I have all the ethernet ports used.  But ethernet cable goes from the nighthawk to the  fios quantum gateway so that we can enjoy on demand and DVR.  Just to note I did have to go into the fios gateway and change its IP to 192.168.2.1 and it is currently set in bridge mode with both wifi channels of.

 I need only a couple more ethernet ports and was wondering if I can use the fios gateway as a switch with its 4 empty ethernet ports? And will I run into any double nat issues?

I am new at this so please bare with me lol.

Thanks 

Shane