Don't know if this can be related to site moving to a new server. For some time i can't connect to igniterealtime.org xmpp server via IM Gateway in Spark. Though i can login directly using igniterealtime.org as a server on a login page. Also SparkWeb doesnt connect to a server (Try it live! http://www.igniterealtime.org/projects/sparkweb/index.jspc)
In IM Gateway settings i have igniterealtime.org as a Host. Maybe it was changed?