The host warns when its UDP socket-buffer grant is small (Linux caps SO_SNDBUF at
net.core.wmem_max, ~208 KB by default). Validated zero-loss at 5K even at that cap,
but raising it gives send-side headroom for higher bitrates / concurrent sessions.
Referenced from the headless-Steam appliance setup. macOS clients need no tuning.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
