Check these in order

  1. Is the stream key current? YouTube and Facebook both issue a fresh stream key per broadcast if you're using "Go Live" scheduling rather than a persistent key. Copy the key from the live control room / stream setup page for today's scheduled stream, not a saved one from last week.
  2. Is the destination event actually created? On YouTube, you need a scheduled live event in Studio before OBS can connect to it. On Facebook, the same applies for a scheduled Live Producer stream.
  3. Network connectivity. Open a browser on the same machine and load any webpage. If that fails, it's the building's internet, not OBS — check the router/modem before going further.
  4. Server region. In OBS Settings → Stream, try switching the "Server" to the primary/auto-selected region rather than a manually chosen one — a saved custom server occasionally becomes stale.

"Failed to connect to server"

This almost always means the stream key/server pair doesn't match, or the platform-side event isn't live/ready yet. Re-copy the key fresh, paste it into OBS Settings → Stream → Stream Key, and confirm you clicked "Start Streaming" on the platform's side (YouTube/Facebook) if their interface requires arming the event first.

Stream shows black or frozen on the platform

Before next Sunday Do a 2-minute test stream (private/unlisted) the night before for anything other than a routine Sunday — new equipment, a new laptop, or after any software update.