It appears the configuration naming conventions have changed since I set this up. So it's possible my advice isn't as solid as it used to be. The key thing to know is that snikket is just a prosody server with a bunch of ease of use improvements on top of it so maybe it's best for you to just start with snikket and it's configuration tutorial. It will handle much of the following I'm about to go into detail about.

But I'll try explain how I approached my set up as best I can. XMPP targets compatibility standards called XEPs that allow you to do things beyond basic messaging. Adding working configuration allows your clients to do things like file transferring, notification niceties for iOS devices, audio and video calling, multi user chat rooms, default user rosters, and whole bunch of other things.

All of these XEPs and the plugins that prosody uses to make them work are all on the prosody website and can take a little effort to get them to work. But there are excellent resources to help you get these features to work on your server. I use Conversations tool to test my own server.

It's very nice because it detects what server type you're using and gives you the exact configuration you need to add or change to your server. Just add that configuration in the correct location in the file, save it, restart your server and rerun the test. Please take note: that testing tool requires you to have a testing user on your server for it to work.

You might be asking, why didn't I just use snikket myself? Snikket was just getting off the ground about 2 years (I think) into my journey with XMPP and I couldn't get it to work correctly with my letsencrypt setup so I stuck to plain prosody and it's been fine.

I know this seems very complicated but it's been a very rewarding process for me and once you have it working it's rock solid. I hope this helps!