Websocket disconnects during BYOC load test

Trying to understand why Websocket connections drop during high concurrency load tests on our BYOC Edge setup. Using JMeter with 200 threads hitting the media server in ap-southeast-1. Getting immediate 1006 close codes after 10 seconds. JMeter config uses standard WebSocket samplers with keep-alive. No CPU spikes on the Edge node. Is there a specific connection limit for BYOC media servers that I am missing?