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CustomLag
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CustomLag

by scrythe · on Modrinth

Fabric mod to simulate lag for servers and single player worlds by delaying packets from sending and receiving

Which Minecraft do you have?

Every version of the game needs its own build. Pick yours, then download — the wrong build installs fine and then does nothing in the game. This mod is built for Fabric only.

⬇ Download for 1.21.11⬇ Download for 1.21.9–1.21.10⬇ Download for 1.21.6–1.21.8⬇ Download for 1.21.5⬇ Download for 1.21–1.21.4
I don't know my version or loader
Open the Minecraft launcher and look at the profile you play on — it names both, like fabric-loader-1.21.4. The version also shows in the bottom-right corner of the game's main menu.
No loader in the profile name? Then it's plain Minecraft, and these mods won't run — you need Fabric or NeoForge installed first.
CustomLag — screenshot 1
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About the Mod

This Mod simulates lag by delaying the processes of receiving and sending packets. This is done by injecting a ContextHandler inside the ChannelPipeline of a minecraft connection. This mod works only for servers and single player worlds.

Usage

To set or change the latency/ping for a player, just use the lag command:

/lag set <playername> <latency>

Setting lag will be saved to a toml file, so even after restart, the settings will remain. You can also set the lag of offline players (who have not currently joined yet.)

In order to remove the lag of a player, you can use:

/lag remove <playername>

(this removes the ContextHandler that delays packets from sending)

Some additional commands are:

There are also some addional quality of live -ish commands, like increase the keep alive / ping packets interval, to find more, just enter

/customlag
Quick facts

Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.

Verified by MCModsHub

These come from our own check of the pack file, not from the source page.

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