Stuck on Certificate Validation 502s during WebRTC Load Test

Stuck on a weird SSL handshake failure while stress testing WebRTC signaling throughput. JMeter 5.6.2 running from a Singapore-based instance hits 502 Bad Gateway errors on wss://webapi-gencdn-usw2.platform.dev.vonage.com when concurrent connections exceed 200.

The setup uses BYOC Edge 24.1.0 in the Asia Pacific region. Initial connections work fine, but as the ramp-up phase kicks in, the WebSocket handshake fails with SSL_ERROR_BAD_CERT_ALERT. This happens even though the client certificates are valid and rotated monthly.

Here is the JMeter HTTP Request Defaults config:

http_request_defaults:
 protocol: wss
 host: webapi-gencdn-usw2.platform.dev.vonage.com
 path: /v2/conversations
 thread_count: 500
 ramp_up: 60
 keep_alive: true
 ssl_version: TLSv1.2

Is there a connection pool limit on the platform side that triggers this? Or is the load balancer dropping connections due to certificate verification overhead? The logs show no obvious rate limiting (429s), just immediate connection resets. Any insights on WebSocket capacity planning for this endpoint?