Thanks for the response by the way and yes that did fix it.
TL;DR: is there documentation anywhere that explains what each anticheat type number is checking for?
The type 24 above was on a vanilla server and we've since started a modded play through so I've not written up the following as bug reports but we've been getting kicked for type 21, 23 and I think 12 since going modded which is fine I just disable each one and now I've just gone and disabled all of them, it's a private server for trustworthy friends so I'm fine having all the anticheat turned off. It'd be nice to know what exactly I'm turning off though but I can understand if the anticheat stuff is obfuscated for a reason.