Minecraft version - 1.21.1
Mod loader - neoforge 21.1.169 - 21.1.205
Mod version - 2.2.4 - 2.2.5
I am using the latest version available - yes

Describe the bug

Hello author, this is a very strange bug related to the number of mods in the modpack. I created a modpack myself, but I found that once the number of mods (as shown in the bottom left corner of the main menu) exceeds 379, I cannot connect to the server, although local play still works fine. To address this, I tried removing high-risk mods like Sinytra, but the issue persisted. It wasn't until I removed Better Combat that the problem was resolved. Since triggering this issue requires over three hundred mods, it's impossible for me to check one by one whether other mods are affecting it. I will provide the debug file from when the server connection failed, as well as my mod list. I hope you can help me check if there might be a solution from your mod.

Additional context

disconnect-2025-09-30_02.37.13-client.txt

Likely a Carry On issue:
Tschipp/CarryOn#751
Tschipp/CarryOn#777

Or rather, it may be because both Carry On and Better Combat are adding a data tracker to players via mixin which might produce inconsistent results, in this case triggered by having a sufficiently high mod count.

That’s probably why Canary crashes with Carry On due to this usage, see here:
Tschipp/CarryOn#829
(Not that I would recommend using Canary)

yeah was having a similar issue couldn't connect to server disabled carryon now working just fine in my pack ive been working on

Thank you for the valuable information @muon-rw