MQTT Client Not Receiving Response via Load Balancer
Problem
This article helps diagnose and resolve issues where an MQTT client does not receive responses from HiveMQ when accessed through a load balancer (LB)—especially when TLS termination is involved.
Symptom:
MQTT client (e.g., Postman, MQTT CLI) does not receive a response or encounters an error when publishing messages via a load balancer.
When connecting directly to the HiveMQ broker (bypassing LB), message publishing works as expected.
HiveMQ does not log any incoming requests from the client during failed attempts.
Solution
One or more of the following may be the cause:
Root Cause Description | Solution and How to Confirm |
|---|---|
TLS terminated at LB, not passed through | Check LB settings and ensure forwarding works |
Client blocked from accessing LB TLS port | Verify firewall or network policies |
Request not reaching HiveMQ | Confirm with broker logs or trace recordings |
Using a non-native MQTT client | Switch to MQTT CLI or another compliant client |