This is a Velocity plugin that makes it possible to host a modern Forge server behind a Velocity proxy!
Unlike other solutions, this plugin does not require any special modifications to the backend server nor the client. (The player doesn't need to do anything)
Velocity has now added built-in support for newer mc versions and therefore don't need Ambassador. You might still need PCF mod on the server-side, for more info please visit: https://github.com/adde0109/Proxy-Compatible-Forge
1.16.5: https://github.com/Just-Chaldea/Forge-Client-Reset-Packet
1.18.2+: https://www.curseforge.com/minecraft/mc-mods/forge-client-reset-packet-forward
This is an issue with Client Reset Packet Mod being partly incompatible with certain mods on the client. Please remove incompatible mods on the client if you have this issue. (Yes, this also includes client-side only mods.)