Very honestly, I had the same issue (not because of the kids, but because i wanted it to work 
)…
I scrapped the server and use Yatsee as a Kodi remote control on my android devices.
The thing is, with yatsee, you can buy (I got it for 3 euro or so), the extension allowing you to actually watch/listen to the medias on your local device (here android phone/tablet).
Way easier…
In case you want to use a different Kodi instance, then you’ll need a Database server somewhere (Using mariadb/mysql) on my NAS - and I have 4 devices accessing the same DB and Medias for Videos, and 3 more for Music only
And of course the kids access music etc. through Yatsee too.