OBS "Failed to connect to server": causes and fixes

What it looks like in your log

127.0.0.1:1999/dead is offline. Try a different server (ECONNREFUSED).
[rtmp stream: 'simple_stream'] Connection to rtmp://127.0.0.1:1999/dead failed: -2

Why does OBS say it failed to connect to the streaming server?

OBS opened a connection to the server in Settings → Stream and the other side did not accept it. ECONNREFUSED means nothing is listening on that address and port (wrong port, ingest not running or a firewall rejecting it). ETIMEDOUT means the packets never got an answer (blocked, wrong address or no route). "failed: -2" is OBS's generic connect failure; "-1" is a bad URL or path and "-3" is a server that rejected the stream, usually a wrong or expired stream key. The error appears in the log within a couple of seconds of pressing Start Streaming, so the stream never goes live and nothing is dropped or skipped, which is why the usual frame counters look clean.

How to fix it

1. Open Settings → Stream and re-copy the Server and Stream Key from your platform. For a Custom server use the full URL including rtmp:// or rtmps:// and the port (1935 for RTMP, 443 for RTMPS).
2. Test the address from the same PC: ping the host, or run Test-NetConnection host -Port 1935 in PowerShell. If it fails, the problem is the network path, not OBS.
3. If you stream to your own server (nginx-rtmp, MediaMTX, SRS, a media server on your LAN), make sure it is running and listening on that port and that its firewall allows the connection.
4. Allow obs64.exe through Windows Firewall, and turn off VPN, proxy or antivirus web shields while you test.
5. Try a different ingest region or server, or another network (a phone hotspot is a quick test), then regenerate the stream key if the platform rejects it.
6. Upload the log again after a test: StreamRx shows whether OBS connected successfully this time.