I have followed Amazon EC2 to setup latest Freeswitch on an EC2 instance with an internal and public IP.

When I dial out to an external SIP endpoint I can see sometimes the internal IP in the candidates list, sometimes the external IP - same configuration, just retrying the same endpoint.

Internal IP:

a=candidate:5446536444 1 udp 659136 172.25.36.61 29668 typ host generation 

External IP:

a=candidate:1181434720 1 udp 659136 13.238.218.223 20132 typ host generation 0

How can I debug this and does anybody have an idea why this is inconsistent with the same config when redialing same endpoint?

Thanks for your help

Sven