Does Openfire STUN plugin require 2 external IPs or 2 LAN IPs?

Can anyone clarify that please: does STUN require that the box running openfire have:

1. two NICs with different local IP addresses? or

2. two local IP addresses on the same NIC? or

3. two external IP addresses translating ports 3478/3479 respectively to the OF box?

Or point me at the documentation where that is explained.

The issue I am having is that the clients using ICE cannot place voice calls using my server, while the clients where ICE is disabled can place calls, but cannot hear voice in any direction.

Thank you