Simple answer: Use Primary YouTube Ingest Server unless you have a specific reason not to.
What the options mean:
| Option | Meaning | Use when |
|---|---|---|
| Primary YouTube Ingest Server | Main YouTube RTMPS ingest endpoint | Normal streaming |
| Backup YouTube Ingest Server | Secondary ingest endpoint for redundancy | You are sending a second, matching stream from another encoder/network |
| Primary YouTube Ingest Server — legacy RTMP | Older, unencrypted RTMP endpoint | Only if your encoder cannot use RTMPS |
| Backup YouTube Ingest Server — legacy RTMP | Older RTMP backup endpoint | Only for legacy backup workflows |
Primary vs backup: Backup is not a better/faster server. It is for redundancy. YouTube expects the backup stream to match the primary stream’s settings: resolution, codec, bitrate, frame rate, keyframe interval, audio codec, sample rate, and so on. YouTube’s error docs specifically warn that primary and backup streams must match. (Google Help)
RTMPS vs legacy RTMP: RTMPS is RTMP over SSL/TLS, so it is the modern secure option. Google’s YouTube developer docs describe RTMPS as regular RTMP tunneled through an SSL connection. (Google for Developers) Legacy RTMP is older and unencrypted; use it only for compatibility with older encoders.
Best choice in OBS: Choose:
YouTube - RTMPS → Primary YouTube Ingest Server
Use Backup YouTube Ingest Server only if you are also running a separate backup encoder/connection into YouTube. Do not switch to backup just because the primary has issues unless YouTube/OBS support specifically tells you to; it is meant as a second simultaneous feed, not a manual “alternate server.”
