What is the cause of the problem with TLS?

Question

go

Connect to jabber server:

net.Dial("tcp", s.Addr+":5222")
//....
  config := tls.Config{InsecureSkipVerify: true, PreferServerCipherSuites: true}
tlsConn := tls.Client(s.Conn, &config)
hs := tlsConn.Handshake()
fmt.Println(hs)

remote error: protocol version not supported
I didn't really deal with SSL before, from the error, in principle, it is clear that someone (server or standard client) does not support someone's version of the protocol. But how do you know what exactly is the problem? Well, solve it, if possible.
For example, I took the null.pm server, but the same problem with everyone where SSL is required by default.