Bungee/Waterfall To a Modded Server

Hello, I was wondering if anyone has successfully connected a vanilla lobby to a modded server? I have tried using various methods, but whenever I try to connect to the modded, it simply say “Connecting to X server” then right under it, almost immediately, it says “Disconnecting from X server” with no visible change in game. Anyone know what I am doing wrong or how I might get around this?

Does the modded server have any logs? There might be some information in there.

It might be this if you tried using Bungee first: