JMeter WebSocket Handshake 403 on BYOC Edge Provisioning

Could use a hand troubleshooting this sudden spike in 403 Forbidden errors during our latest load test against the Genesys Cloud BYOC Edge provisioning API. We are running a JMeter script designed to simulate 500 concurrent WebSocket connections for a single edge deployment in the ap-southeast-1 region. The test was stable for the first 10 minutes, but as we ramped up to 300 concurrent users, the handshake phase started failing consistently. The logs show a clean 101 Switching Protocols response for the initial batch, but subsequent requests within the same minute return 403 with a generic ‘access_denied’ payload. This is strange because the OAuth tokens are valid and refreshed every 55 minutes, well within the expiry window. We are using the latest public API spec for the v2/boundaryControl/edges endpoint.

The environment is a standard Multi-Org Premium setup with BYOC enabled. We have verified that the edge certificate matches the private key uploaded to the platform, and the firewall rules allow outbound traffic on port 443. The issue seems isolated to the WebSocket upgrade phase rather than the data transmission. We tried increasing the JMeter thread group ramp-up time from 10 seconds to 60 seconds to reduce the initial burst, but the 403 errors still appear once the concurrent connection count exceeds approximately 250. The error response does not provide much detail, just the standard OAuth error structure. We are wondering if there is a hidden per-edge WebSocket connection limit that is being enforced at the load balancer level before the request even hits the application logic.

Here is the relevant JMeter thread group configuration: Thread Count: 500, Ramp-Up Period: 60s, Loop Count: Infinite. The sampler is an HTTP Request pointing to the wss endpoint with the Authorization header set to Bearer . We have also enabled debug logging on the JMeter side, which shows the request is sent correctly with all required headers. The response time for the failed requests is under 50ms, suggesting the rejection happens very early in the chain. Is there a specific rate limit or concurrency cap for WebSocket handshakes on BYOC edges that we are missing? Any insights into how Genesys Cloud handles these concurrent upgrade requests would be greatly appreciated. We are currently blocked on validating our capacity planning model for the upcoming quarter.

It depends, but typically the 403 on WebSocket handshakes during load tests is not a BYOC Edge issue but a platform rate limit on the WebSocket upgrade endpoint. The Genesys Cloud API enforces strict concurrent connection limits per organization or IP range. When hitting 300 concurrent users, the platform blocks the handshake to protect the signaling server. The fix is to adjust the JMeter test to ramp more slowly or implement a retry logic with exponential backoff for the 101 switch. Also check if the edge is configured with a specific IP whitelist that might be blocking the load generator IPs. The documentation suggests keeping concurrent WebSocket upgrades under 50 per second for stable performance. If the issue persists, check the Genesys Cloud admin portal for any IP-based blocks or firewall rules triggered by the sudden traffic spike.