Use a query API key for reading SigNoz, not the ingestion key, and test the filter expression in the Logs Explorer first when queries return nothing. Point readers at the SigNoz API port, never at the collector ports. If the v5 query endpoint 404s, upgrade SigNoz past 0.87.0 rather than working around it.

Context: A SigNoz integration troubleshooting table documents the address and key traps. A 401 or 403 on every tick means the wrong key type was used: an ingestion key where a query API key belongs, or a revoked key. A 404 on /api/v5/query_range means the SigNoz version is older than v0.87.0 and lacks the endpoint. When logs exist in SigNoz but a reader sees no new entries, the reader address likely points at the OTLP collector ports 4317 or 4318 instead of the SigNoz UI and API port.