Unable to support Forge mod server 1.20.1

[ccnetcore]

Prerequisites

• I have read and understood the user manual
• I made sure I am running the latest development build
• I tried to look for similar feature requests before opening a new one

Console Client Version

Latest

Describe your problem

Unable to support Forge mod server 1.20.1

Suggest a possible solution

No response

Attach screenshot here (If applicable)

No response

Minecraft Version

No response

Device

None

Operating System

None

[milutinke]

The client doesn't yet officially support 1.21.1, there is my custom separate branch for it, but I haven't done anything related to Forge.
Vanilla is the primary focus, we'll deal with any Forge changes only when the Vanilla version works.

[CyanKhaos]

I too cannot join a modded 1.20.1 (Not 1.21.1) forge server, it says

Ignoring Unknown FML2 LoginMessage channel: tacz:handshake
Ignoring Unknown FML2 LoginMessage channel: framework:handshake
Received FML3 Server Mod Data List
Received FML2 Server Mod List
Sending back FML2 Client Mod List
Acknowledging FML2 Server Registry: minecraft:command_argument_type
[MCC] Login failed :
[MCC] Unexpected custom data from client
[ERROR] Failed to login to this server.

Being able to use this for a modded server would be cool for moderating/using commands on a server without having to fully open up minecraft

[myxxmikeyxx]

I would love that too. I have a modpack that I would love to AFK for a bit on my server. also for 1.20.1