according to the Jabber-Manifesto all Jabber-Admins have agreed to completely encrypt the XMPP Network. As such only encrypted connections are possible, that is server to server and client to server. You will need to enable encryption in your client if you have not done so before.
alpha-labs.net was offering both encrypted an unencrypted connections between servers, but not all server administrators offered those secured connections on their end. During this XMPP-Network wide switch it might be possible that some connections between servers will be disrupted as, starting today, alpha-labs.net will no longer establish or accept unencrypted connections.