The short version
Plug the streaming computer into the router with an Ethernet cable: OBS says Wi-Fi may be unstable for streaming and recommends a wired connection. Then check your upload, not your download: YouTube asks you to keep about 20% of it free, and Twitch an upload 30% above the stream’s bitrate. The upload calculator does that sum for your platform.
If the stream drops frames only when someone else in the house is uploading, downloading or on a video call, the router is probably holding too much traffic in its queue. That is called bufferbloat, and a router setting called Smart Queue Management (SQM) is the fix.
Upload is the number that matters
A stream goes up, not down, and most home connections upload far more slowly than they download. Run a speed test on the streaming computer, over the cable you will stream on, at the time of day you usually go live. YouTube adds that a fast connection shared by many people can leave each of them much less.
Everything else that uploads in the house takes from the same line: cloud photo and file backups, video calls, game clips being shared. Pause what you can while you stream, and count the rest in the upload calculator’s “upload the rest of the house uses” field. OBS’s own starting point for the video bitrate is 75% of your total upload, within the platform’s limits.
Ethernet, not Wi-Fi
Wi-Fi shares the air with every other device and network nearby, and a short dropout that a web page never shows is a dropped frame on a stream. OBS lists streaming over Wi-Fi among the hardware causes of dropped frames, and its fix is a wired connection.
If a cable can’t reach yet, rehearse on Wi-Fi in a private or unlisted stream at your normal bitrate, with the house as busy as usual, and watch the network counter in OBS’s Stats window. If it climbs, the cable comes first, before any setting.
Bufferbloat: when the house is online, the stream stalls
Routers keep a queue of data waiting to go out. When that queue is too large and the line is busy, every packet waits behind it, so the delay jumps and the stream’s data arrives late; Wikipedia’s article names voice calls, video chat and online games among the first things to suffer. A speed test that reports only speed hides it: what matters is the delay while the line is full.
To see it, use a test that measures delay under load and gives a bufferbloat grade: Waveform’s Bufferbloat Test is one, and OpenWrt also names Speedtest, LibreQoS and Cloudflare’s test. Run it with nothing else using the internet, save the result, and compare the delay while downloading and uploading with the delay at rest.
- Turn on SQM. On a router running OpenWrt, its guide says: enter download and upload speeds of 90% of what the idle test measured, choose cake as the queueing discipline, test again, then raise the speeds until the delay comes back and step down a little.
- No SQM in your router? Look in its manual for a QoS or bandwidth setting that limits upload and download, or ask your provider. Wikipedia also lists queue algorithms such as FQ-CoDel; a router that names one of them in its settings can manage its queue.
- Test the stream again with the house busy: the network counter in OBS should no longer climb.
OBS’s own network settings
OBS Studio’s troubleshooting guide for dropped frames and disconnections, in its order. Try one at a time and rehearse after each.
- Try another server in Settings, Stream. On Twitch for Windows, OBS points to TwitchTest for the server with the best score.
- Lower the video bitrate in Settings, Output, within what your platform publishes.
- Settings, Advanced, Network: on Windows, tick Enable network optimizations and then Enable TCP pacing; leave Bind to IP on Default; as a test, set IP Family to IPv4 only, and put it back if nothing changes.
- Dynamically change bitrate to manage congestion (Beta) lowers the bitrate instead of dropping frames. OBS calls it a last resort: it hides the cause and the picture gets softer.
- Outside OBS: pause a VPN, test with the firewall or antivirus briefly off and add an exception for OBS, turn off network “boost” tools such as Lenovo Vantage’s Network Boost (with Killer network cards, reinstall only the drivers), and update the network driver.
- Restart the modem and router, and if the drops continue, call your internet provider: much of the route to the platform is in its hands.
Prove it before you go live
Run a private or unlisted rehearsal for at least as long as a normal stream, with the house as busy as it usually is. Watch Dropped Frames (Network) in OBS’s Stats: fix OBS dropped frames tells it apart from rendering and encoding lag. On Twitch, Twitch Inspector shows how steadily your stream arrived.
Questions
Is my internet fast enough to stream? At Twitch’s 1080p, 60 fps figure, 6,000 kbps of video and 96 kbps of audio, Twitch’s rule asks for about 7.9 Mbps of upload. The upload calculator works it out for any platform and output.
Do I need a gaming router? No particular router is needed. What helps is a wired connection and a router that can manage its queue (SQM); check for that in the manual of the one you have before buying another.
Does download speed matter? Only for everything else: games, chat and alerts. The stream itself is upload.
Can I stream over a phone’s mobile data? It works when the upload is steady, but mobile upload changes with signal and the people around you. Rehearse at the place and time you will stream.