Network Investigation
Games need upload too, not only download.
When uploads, livestreams, cloud sync, meetings or other devices fill the upstream queue, game input packets can be forced to wait, causing latency, jitter and short stutter.
Uploads affect gaming because games constantly send your actions to the server.
If the upload direction is saturated, game packets cannot leave your network quickly. You may feel delayed skills, late shots, rubber-banding, broken voice chat or short disconnects.
Many people think games mostly download data, but online games are two-way real-time communication.
Movement, attacks, shooting, skills, turning and item actions all need to be uploaded to the server. The server then confirms and synchronizes the result back to you and other players.
Many home, dorm, mobile and shared networks have much less upload bandwidth than download bandwidth.
You may have hundreds of Mbps for download, but far less for upload. Once someone uploads video, livestreams or syncs cloud files, the upstream queue can fill quickly.
Game packets are small, but they are time-sensitive.
When the upload queue is long, game packets wait behind large files, video streams, cloud sync and traffic from other devices. The packets may eventually arrive, but they arrive too late for smooth gameplay.
Upload-related gaming lag is often connected to bufferbloat.
When a router or internet link queues a large amount of upload traffic instead of controlling delay, real-time game packets also wait in line. The bandwidth may look available, while latency rises sharply.
Compare gaming ping when the network is idle and when a device starts uploading or syncing files.
If ping rises, jitter increases or voice chat becomes choppy during uploads, then returns to normal after uploads stop, upstream congestion is likely affecting the game.
Games are not only hurt by slow downloads. They are also hurt when the upload direction is blocked.
For real-time games, upstream stability is critical. Every action needs to leave your device on time for the game to feel responsive.