I Built a 700-Person Video Call Without Zoom. Here's Every Mistake I Made

TL;DR: I ditched Zoom for a self-hosted solution using Janus WebRTC Gateway. It works, but I hit three painful production issues: a signaling storm that crashed the client, silent session timeouts that confused users, and a ulimit that killed me at participant #200. This post covers the full architecture, the API flow that actually matters, and a pre-flight checklist before you try this at scale. My company needed to host a 700-person all-hands call (on-premises, no data leaving the corporate network, recordings on our own disks). The usual answer ("just use Zoom") wasn't on the table. Compliance requirements were strict, and this landed on me. So I had to own the stack. Under the hood: Janus WebRTC Gateway, an open-source C-based media server from Meetecho, GPLv3, on GitHub since 2014. What I write below applies to any WebRTC infrastructure; Janus is just what I ran. Why a Media Server at All? In a naive P2P mesh, each participant sends a video stream to every other participant. Conne