Direct answer

A working Geyser crossplay installation needs a compatible Java backend, a reachable Bedrock UDP listener and the intended authentication method. Verify all three separately before investigating Bedrock client errors.

Recommended procedure

  1. Confirm the Geyser variant is installed on the correct backend or proxy, and check its startup log for the listening UDP port.
  2. Ensure the Java backend accepts the Java protocol version Geyser currently imitates; add official compatibility tooling only if required.
  3. Open the specified Bedrock UDP port on your router, provider firewall and host firewall.
  4. If using Floodgate, check its placement and keep any shared authentication key confidential.
  5. Test Bedrock on a different network; compare Bedrock results with a normal Java client login.

Why this matters

Java’s normal TCP port and Bedrock’s UDP port are different paths. A successful Java login does not demonstrate that Geyser is listening or externally reachable.

Practical example: Example: a Bedrock client can see the server in the list yet fail during login. This is different from UDP timeout: the request has reached the bridge but authentication or version negotiation might fail. Collect the Geyser console line at that moment and compare it with a normal Java login.

How to verify the result

  • Use Geyser’s documented connection-test command when available.
  • Confirm a Bedrock client can join, interact with the world and retains the expected account identity.
  • When only Bedrock fails, examine Geyser logs and UDP networking before altering Java online-mode.

Version and compatibility notes

  • Geyser requires current releases to support newer Bedrock protocol changes.
  • Client-required Java mods are not automatically translated by Geyser.

Official references

These sources were checked for the current MSH revision. Version-sensitive details should always be confirmed against the project documentation for the release you run.

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