Issue to connect in Asterisk server

I had 2 Asterisks servers conected that lost connection today (nov4) by no apparent reason from server (Asterisk1) to client (Asterisk2).

Server is running in a Amazon AWS EC2 Ubuntu 16 with Asterisk 13 and PJSIP.

How can I detect if have any firewall or how to do a traceroute from Asterisk 2 to Asterisk 1 to detect where is the problem.

Some observation:

  • Asterisk2(client) can ping Asterisk1(server);
  • Other clients are connected in the Asterisk1;
  • Asterisk2 is used behind a NAT;

I was using this connection by one week and stopped today.

Regards

start with pjsip show contacts command and verify the address and port is reachable between the 2 endpoints, disable any firewall temporarily