Now that I've gotten as far as cleaning up the ES, which improved the performance by millions of %, thankyou for the insights into what the problem was!
Instead of having 35000 shards, we now have <700, and the ELK is performing great.
Now I'm a bit more confident in pooring data into it
I'm actually beginning to show it to my developers (we're currently picking up errors from their coding into the ES, so they get a super overview over all the servers, and what the problems might be).
This also presents my next challenge.
I want to remove the 'add sample data' etc. from the homepage, and I've looked in the guide, and I don't see where to do that. Currently the homepage shows all sorts of 'nice' things like how to build this and that, and add sample data etc. I really don't want to show that.
I have set it up in the docker-compose, that the dashboard we've created is the one it opens on, so at least that makes it easier for them.