Engineering notes
What we hit building WebRTC systems that have to survive real networks — written up so the next person loses less time to it.
A complete, working coturn configuration for WebRTC — relay port ranges, time-limited credentials, TLS on 5349, the external-ip trap on cloud VMs, and the SSRF hardening almost every guide leaves out.
A diagnostic walk through ICE: what host, srflx and relay candidates mean, why symmetric NAT and CGNAT break direct connections, and how to read candidate pairs to find the actual failure.
Why peer-to-peer stops working at four participants, what an SFU actually does, when an MCU is still the right answer, and how the choice drives your bandwidth and CPU bill.
What Nuve, ErizoController, ErizoAgent and ErizoJS each actually do, why Licode deployments become hard to build years later, and how its concepts map onto mediasoup and LiveKit if you decide to migrate.