Not entirely sure this is the best place to report this, since the JIRA does not allow for user submitted bug reports.
It appears from snooping the wire that Server to Server messages the default namespace rather than the jabber:server namespace. This causes
at least Vysper issues as it expects the messages to be in the “jabber:server” namespace. I have not completely read the protocol this could be expected behaviour, if so please let me know, and I will submit a patch to Vysper.
An example message lacking the jabber:server namespace, obtained from snooping the wire is below, although the audit logs show the same issue.