Requested Feature

Allow overriding forwarding mode for specific servers

Why is this needed?

With bungeecord getting more and more outdated its support will inevitable start to fall off. For example, Fabric does not have a notable maintained mod for bungeecord forwarding. This means if a server network wanted to host a <=1.12.2 server and fabric 1.21.4 server it would be impossible without disabling forwarding entirely.

Alternative Solutions

A: Completely disable forwarding: Loses all benefits of forwarding and with offline UUIDs would be unviable for existing setups
B: Middleman proxy: Technically possible with viaproxy (it strips the forwarding info so offline servers work), however there is no decent solution for this and this is very hacky

Additional Information

Duplicate of #1145 - Making new issue due to former being closed unplanned and as to use new format
Technically duplicate of #566 - This issue is more direct and former has been inactive for 3.5 years

The main issue pointed out in #1145 is incompatibility with existing configuration. This is not necessarily the case. If instead of requiring each server have its mode set manually instead an optional overrides table is provided then this could be supported by checking the overrides for a forwarding mode and if one isn't specified use the default (existing) setting