The "connection lost" message is usually caused because the URL at which you are visiting a NodeBB forum is not the "url" value set in config.json
Unsolved NODEBB Forum A course on deleting topics permanently
Recently, when I try to permanently delete a topic, I get the following message:
And the forum crashes and needs to be restarted.
I use a remote mongo database, and I have the option to run commands on it using Robomongo.
What plugins do you have? Try disabling all plugins.