Create a file */etc/munin/plugin-conf.d/loggrep_prosodys2sfails* (we don't want change the standard file */etc/munin/plugin-conf.d/munin-node* as future updates might want to undo the changes) and put the following into it:
env.title Prosody failed encrypted S2S communication
```
Edit */etc/munin/munin.conf* - in our case we have a Munin host named *tethys.hot-chilli.net*, please add it under the specifications for your own host: