You're having DNS issues on your machine.Attached the full log.
You're having DNS issues on your machine.
Please make following settings in Sharp Messenger as a workaround.
AutoResolve = False
Server = xmpp.l.google.com
[10:51:23.645 D] [Sharp Messenger] Error is '<error xmlns="jabber:client" type="cancel" code="503"><service-unavailable xmlns="urn:ietf:params:xml:ns:xmpp-stanzas" /></error>'.