TLS 1.1 is working but not TLS 1.2 wtih Openfire 4.1.3

Following is the current setting for encryption protocols
image

We have developed a C# client with MatriX library.
When we use TLS 1.0 | TLS 1.1 (in client) for communicating is working seamlessly.

Now we are enforcing our client/server to use TLS 1.2 for better security, but it doesn’t seem to work.

Here is the response from server and not proceeding beyond this point.

SEND: <stream:stream xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client" to="dev-xmppcollab-eus.cloudapp.net" version="1.0" >
RECV: <stream:stream xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client" from="dev-xmppcollab-eus.cloudapp.net" id="d89cm4rkb" xml:lang="en" version="1.0" >
RECV: <stream:features xmlns:stream="http://etherx.jabber.org/streams">
  <starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls">
    <required />
  </starttls>
  <mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
    <mechanism>PLAIN</mechanism>
    <mechanism>EXTERNAL</mechanism>
  </mechanisms>
</stream:features>
<starttls xmlns="urn:ietf:params:xml:ns:xmpp-tls" />
RECV: <proceed xmlns="urn:ietf:params:xml:ns:xmpp-tls" />

What are the specific changes for TLS 1.2 that I need to do from Server side?