IP TFTP telephony not connecting to server?

What do you learn from doing #1 in Rulz?

Cheers - Bob

How does the phone know what server to use?   If it is asking the network for that information, it may not be getting the information it needs in reply, and therefore never attempts to contact your intended server.

The logs will tell you whether the phone is actually attempting to do what you assume it is doing.

We check the logs and couldnt find anything related to the mentioned problem. Problem is when communication wont return to SSL VPN remote access Client - Open VPN (to Cisco IP communicator). When this IP communicator tries to connect with server, communication goes to the server and when going back from server to a client, it stops on UTM. Apparent problem is TFTP communication, we can only see this with TCPdump - we can't see anything from the logs. Because of this problem IP telephony won't establish a connection, because for succesfull connection it needs configuration file from TFTP server.

We managed to establish communication only two times randomly but nothing was done/changed. After restarting communicator connection stopped working again.
We already tried turning off every security settings (IPS, Web Protection, Advanced Threat Protection,...) and firewall rule was (any to any) allowed for SSL remote access tunnel to Server-Client. SSL VPN client has access to all local networks.

We also have a couple of site-to-site VPN tunnels and in this case everything is working properly.

Please check the Connection Tracker helpers to ensure you have the TFTP box ticked?

Network Protection -> Advanced.

Hey, connection tracker helper is turned on from the beginning for TFTP and FTP.