Players often install Bad Packets after hearing it helps Fabric and Forge mods talk to each other. The reality is narrower: it only helps when the specific mod you want was written to use its API.

Check the Mod First

Before adding Bad Packets, look at the mod you actually want to run. Does its page mention Bad Packets, cross-platform support, or Architectury? If yes, that mod has a chance of working across loaders with Bad Packets present.

If the mod page says nothing about Bad Packets or cross-platform packets, adding it will not help. That mod was not built to use the API, so there is no bridge for it to cross.

Practical Setup Steps

Install Bad Packets on both the client and the server, matching the loader you are running. Then install the dependent mod on both sides as well. Launch and watch the log for packet or dependency errors.

If the dependent mod still fails, the problem is usually that the mod itself lacks cross-loader support, not that Bad Packets is missing. In that case, look for a native build of that mod for your loader instead of trying to force compatibility.