OBS Media Source "Disconnected. Reconnecting" and audio lag

What it looks like in your log

[Media Source 'LAN mcast']: Disconnected. Reconnecting...
Source LAN mcast audio is lagging (over by 1200 ms) at max audio buffering. Restarting source audio.

Why does my OBS Media Source keep disconnecting or its audio lag?

OBS reads a Media Source (UDP or multicast, SRT, RTMP, RTSP or an HTTP/HLS URL) with FFmpeg. When packets stop arriving or arrive in bursts, FFmpeg reports "av_read_frame failed" and OBS reconnects the source, and when audio piles up faster than it can play OBS restarts the source audio ("audio is lagging"). The cause is almost always upstream: a sender that stopped or restarted, an unstable network path, a switch that drops multicast without IGMP support, or a source bitrate too high for the link.

How to fix it

1. Check that the sender is running and that the URL and port are right; open the same URL in VLC or ffplay to compare.
2. Prefer a wired connection for the source, and for multicast enable IGMP snooping with a querier or use unicast.
3. In the Media Source properties tick "Restart playback when source becomes active" and set Network Buffering to 2-5 MB; for udp:// URLs add ?fifo_size=5000000&overrun_nonfatal=1.
4. Lower the sender bitrate and keep its audio at 48 kHz stereo AAC so OBS does not need to resample.
5. Use Properties → Reload cache (or toggle the source) after the sender recovers, and update OBS if the failures persist.