Anyone know why the WebSocket handshake returns a 403 Forbidden when JMeter hits 100 concurrent connections?
We are using Genesys Cloud Edge BYOC from Singapore. The first 50 connections succeed, but the rest fail immediately with HTTP/1.1 403 Forbidden.
The 403 error under load is rarely a WebSocket issue; it is usually an authentication token validation bottleneck at the Edge ingress. When JMeter spikes to 100 concurrent connections, the default JWT validation queue on the BYOC endpoint often saturates, causing subsequent handshake requests to be rejected as unauthorized before they even reach the WebSocket layer.
Check your Data Action timeout settings for the JWT generation step. The default 30s is insufficient for high-concurrency scenarios. Increase this to 60s in Architect. Additionally, ensure your ServiceNow integration or custom script handles token caching. If every WebSocket connection triggers a fresh API call to generate a JWT, you are hitting rate limits.
Warning: Do not bypass the 403 by opening the endpoint publicly. The Edge BYOC security model relies on strict token validation. If you see intermittent 403s, inspect the X-Genesys-Auth-Token header in the failing requests. It is likely expiring or being malformed due to race conditions in your token refresh logic.
If you check the docs, they mention that Edge BYOC authentication relies on strict token validation at the ingress layer, which is sensitive to concurrent request spikes.
Does anyone know why the WebSocket handshake returns a 403 Forbidden when JMeter hits 100 concurrent connections?
While the previous suggestion about JWT validation queues is valid, another common cause for this specific 403 pattern in BYOC environments is rate limiting on the OAuth token endpoint or IP reputation checks triggering during rapid bursts. When JMeter initiates 100 connections simultaneously, it may overwhelm the token generation service or trigger WAF rules designed to prevent DDoS attacks. The system interprets the burst as malicious activity rather than legitimate load.
To verify this, check the Edge logs for rate_limit_exceeded or waf_block status codes alongside the 403 errors. If these appear, the issue is not JWT queue saturation but request throttling.
A practical fix is to stagger the JMeter ramp-up time. Instead of 100 concurrent connections instantly, configure a ramp-up period of at least 10-15 seconds. This smooths the traffic profile and avoids triggering defensive measures. Additionally, ensure your client IP ranges are whitelisted in the Edge security configuration. If you are using custom authentication headers, validate that they are correctly formatted for each concurrent thread. Race conditions in header generation can also lead to malformed tokens, resulting in 403 responses.
For legal discovery and audit purposes, always export these edge logs via the Bulk Export API to S3. This preserves the chain of custody for any compliance reviews regarding system performance under load. Ensure your S3 bucket policies allow for large object uploads and that KMS encryption contexts are preserved in the manifest JSON. This approach provides a clear audit trail of the incident and helps in diagnosing whether the 403 errors were due to security blocks or configuration limits.
Check your JMeter token refresh logic. Edges reject stale JWTs hard. Add a correlation variable to fetch fresh auth per thread. See https://support.genesys.cloud/knowledge-base/edge-byoc-websocket-auth for details.