Screenshot 1 of 1. MinecraftHub-generated editorial cover for Connectivity, a voxel diorama around the lime MinecraftHub block
What Connectivity works with.
| Platform | Java Edition |
|---|---|
| Loaders | Fabric, NeoForge, Forge |
| Minecraft versions | 1.16.2, 1.16.5, 1.17.1, 1.18.2, 1.19.4, 1.20.2, 1.21.11, 26.1.2, 26.2, 26.3 |
| Environment | Client, Server |
Connectivity is a lightweight connectivity mod for Minecraft Java on Fabric, NeoForge and Forge. It targets the connection failures that wreck large modded play: login timeouts, decoder exceptions, packet size limits and ghost blocks. It works on both client and server, though it is not required on both sides.
Loaders and versions
- Fabric: Minecraft 1.18.1 to 26.3. The newest build requires Cupboard; some builds for 1.18.1 to 1.19.4 need no dependencies.
- NeoForge: Minecraft 1.19.2 to 26.3. The newest build requires Cupboard.
- Forge: Minecraft 1.16.2 to 1.20.1. The newest build requires Cupboard; some builds for 1.16.2 to 1.19.4 need no dependencies.
What it fixes
- Login timeouts and play timeouts.
- Packet size exceptions during login and play, plus "payload too large" errors.
- Ghost block issues.
- Protection against malformed and malicious traffic.
- Logging of oversized packets, so you can see which source sends them, with warnings when too much data goes out.
The pitch is repair first, diagnosis second. If a pack already runs cleanly you will not notice it. If players keep disconnecting on join, it is the first thing to try.
Network commands
Traffic statistics refresh once per minute and keep up to five minutes of history. Each command takes an optional minute count from 1 to 5, and 5 is the default. Chunk packets normally dominate, and modded packets should rarely exceed them.
- /connectivity packetsClient shows outgoing traffic on the client.
- /connectivity packetsAllPlayers lists the traffic rate of every player.
- /connectivity packetsPlayer <name> breaks down packets by type for one player.
- /connectivity packetsSummary lists everything the server sent, by packet type.
- /connectivity printpacket <type> writes the largest packet of that type to latest.log.
Installation and compatibility
Pick the loader that matches your game, then follow the Java mod install guide and drop the file in the mods folder. Newer releases need the Cupboard library alongside them, so install it too. Only some older Fabric and Forge releases run without it.
Questions about Connectivity.
4 questions
Does Connectivity need to be installed on both client and server?
No. The mod is not required on both sides, but it offers useful functionality for both sides. Files are tagged for client and server, and a client-side command shows outgoing traffic while the server commands list traffic per player, per packet type and as a summary.
What does Connectivity fix?
It targets login timeouts, play timeouts, decoder exceptions, packet size limits, ghost blocks and payload too large errors. It also protects against malformed or malicious traffic and logs oversized packets so you can find which mod sends them.
Does Connectivity need Cupboard?
Newer releases on Fabric, NeoForge and Forge require the Cupboard library. Some older Fabric and Forge releases run with no dependencies, so check the dependency list of the exact file before installing.
How do I see which packets cause lag?
Run /connectivity packetsSummary on the server to list outgoing packets by type, or /connectivity packetsPlayer followed by a name for one player. Use /connectivity printpacket with a packet type to write the largest one to latest.log.
