WebSocket disconnects at 200 concurrent threads

How come this setting causes WebSocket drops in Genesys Cloud?

Running JMeter 5.6.2 from Asia/Singapore. Hitting /api/v2/analytics/conversations/events with 200 threads. Connections drop after 60 seconds with 1006 code.

Server logs show no issues. Rate limit headers look fine. Just pure disconnects.

Any ideas on thread pool sizing or timeout configs?