Over the years, some servers stop working for various reasons, and leave behind broken roster subscriptions that trigger failing s2s connections. This module allows cleaning up such cases by unsubscribing local users from their contacts on those servers. Also works for typos and the like. Use with care.
With the plugin installer in Prosody 0.12 you can use:
sudo prosodyctl install --server=https://modules.prosody.im/rocks/ mod_unsubscriber
For earlier versions see the documentation for installing 3rd party modules