Hello,
Earlier this morning, I attempted to join a friend's server with this mod installed, only for it to kick me while loading chunks with this message in latest.log:

I don't know what's causing it, but we've essentially ruled out all other possibilities for issues (correct forge version, correct java version, same modlist, etc.) except for something in the mod itself. I've attached a copy of my latest.log if it helps.

latest.log

Something like this could happen only if some coremod breaks some basic functionality (i.e. custom registries). Best bet would probably be NotEnoughIds, but could be also any of performance mods.

I tried again with a fresh install of the modpack this is in (Enigmatica 2) through MultiMC, but it still kicked me. Here's a copy of the MultiMC log: https://paste.ee/p/9JOPU

Ok, after looking closely at both logs, it seems server is closing connection before everything is fully initialized, which causes failure in multiple mods. It doesn't really seem like OpenBlocks failure, at least on client side.

[12:43:58] [Netty Client IO #2/INFO] [tconstruct-Config]: Syncing Config with Server
[12:43:58] [Netty Client IO #2/ERROR] [FML]: NetworkDispatcher exception
java.io.IOException: An existing connection was forcibly closed by the remote host

I would suggest checking server logs at the time of login.