Problem

Cannot connect to a vanilla minecraft server.
I get message Client disconnected with reason: You are trying to connect to a server that is not running NeoForge, but you have mods that require it. A connection could not be established.

Version

Client - 1.20.6
Server - 1.20.6 Vanilla
NeoForge - 20.6.100-beta
InvTweaksRefoxed - 1.20.6-1.1.1

is your server running NeoForge?

is your server running NeoForge?

No I've updated the issue to reflect this

is the mod supposed to work with vanilla servers?

The mod page says "This mod allows you to easily manage your inventory, in both single player and multiplayer". And the original mod worked as client-side only mod. So i'm making the assumption that, that is the case.

I could be wrong about this, but that is my understanding of the mod.

I asked around, it did indeed used to work with vanilla servers so I'll look into getting that functionality back.