Edge BYOC WebSocket handshake failing with 403 during JMeter load test in Asia/Singapore

Trying to understand why my WebRTC WebSocket connections are being rejected with a 403 Forbidden error specifically when I ramp up the concurrency in my load tests. We are deploying Genesys Cloud on AWS via Edge BYOC in the Asia/Singapore region. The setup works perfectly fine with low concurrency, like 5 or 10 threads, but as soon as I push the JMeter script to 50 concurrent users, the handshake fails consistently.

The environment is Genesys Cloud v24.4.0. I am using the standard WebRTC SDK for the client side, but for the load test, I am simulating the WebSocket connection directly using JMeter 5.6.2 to avoid browser overhead. The goal is to test the signaling capacity of the Edge deployment before we go live with a major client.

Here is the error snippet I am seeing in the JMeter debug sampler:

{
 "status": 403,
 "error": "Forbidden",
 "message": "WebSocket handshake failed. Invalid or missing authorization token."
}

I have verified that the JWT tokens generated for the test are valid and not expired. The tokens are generated using the same private key used in production. The issue seems to be related to how the Edge service handles concurrent WebSocket upgrade requests. I suspect there might be a rate limit on the WebSocket upgrade path or a connection pool limit on the Edge proxy that is not documented clearly for BYOC setups.

I have checked the network logs and see that the initial HTTP request for the upgrade is sent, but the response comes back as 403 almost immediately when the thread count increases. This does not happen with lower concurrency. Is there a specific configuration in the Edge deployment or the Genesys Cloud admin settings that limits the number of simultaneous WebSocket handshakes? I need to know if this is a soft limit I can request an increase for, or if I am hitting a hard architectural constraint of the BYOC offering.

It depends, but generally… the 403 error during high-concurrency WebRTC handshakes in an Edge BYOC environment rarely stems from the WebSocket protocol itself, but rather from upstream security policies or rate-limiting mechanisms triggered by the sudden spike in connection attempts. When testing with tools like JMeter, especially in a specific region like Asia/Singapore, the rapid succession of requests can be misinterpreted as a Distributed Denial of Service (DDoS) attack by the AWS WAF or the Genesys Edge security layer, leading to automatic blocking of the handshake. You should first verify if there are any IP-based restrictions or WAF rules configured in your AWS account that might be activating under load. Additionally, check the Genesys Cloud organization settings for any specific WebSocket connection limits or rate thresholds that might be enforced per tenant or per edge node. It is also crucial to ensure that the JMeter script is correctly rotating user agents and session tokens to mimic genuine client behavior, as identical headers from multiple threads can trigger fraud detection systems. If the issue persists, consider implementing a gradual ramp-up strategy in your load test to allow the infrastructure to scale dynamically before hitting peak concurrency. Monitoring the Genesys Cloud performance dashboards during these tests can provide insights into whether the issue is related to resource exhaustion or security blocks. Reviewing the CloudWatch logs for your Edge deployment might also reveal specific error codes that can help pinpoint whether the 403 is originating from AWS or Genesys Cloud. Finally, ensure that your VPC endpoints and security groups are correctly configured to allow traffic from the test environment without imposing unnecessary restrictions that could interfere with the WebSocket handshake process under heavy load.