Jabber Message unknown protocol

[Lemming]

Hi,

i'm currently testing Zabbix 3.0.2 on Debian 8 by using the zabbix-repository. Sadly sending messages via my own jabber-server (prosody 0.9.10) using a letsencrypt-certificate fails.

The log of zabbis states:

8134:20160518:201226.084 JABBER: [USER@SERVER] tls handshake failed

Debug-Log on my jabber-server:

May 18 19:11:47 socket debug ssl handshake error: unknown protocol
May 18 19:11:47 socket debug closing client with id: eab4d7bc960 unknown protocol
May 18 19:11:47 c2seab4d7cbf00 info Client disconnected: unknown protocol

My Jabber-server is configured to use TLS1.1 and TLS1.2 and the c2s-test of xmpp.net does not show any errors/problems.
Which protocols does zabbix support? What would be the next step on debugging this issue?

[Lemming]

Found it.

The client build in Zabbix is using TLSv1.0 in its client hello.

http://picload.org/image/rglidlpd/zabbix_jabber.png