When you go over your data allowance, or on plans that manage certain kinds of traffic, packets get delayed or dropped.
Why Speed throttled after the plan’s data runs out, or certain traffic restricted → Effect Packets wait in a queue or get dropped → On screen Lag after a certain amount of usage, especially on mobile
Primary owner External (External) · Also Game team (Server development), Infra team (Network infrastructure)
Game team action items
Reduce game traffic (compression, send only what’s needed).
Infra team action items
If game traffic is delayed or dropped only on a particular ISP, gather evidence and escalate to that ISP.
External action items
Tell players to check whether their plan’s data has run out or is being throttled and whether other apps on the same phone are using data, ask the ISP whether it restricts game traffic.
Ballpark numbers
Korean mobile plans usually throttle to 1–5 Mbps once the data allowance runs out, and cheap plans to hundreds of kbps. The game itself uses little data, but when other apps on the same phone use data, a queue forms in front of the throttling equipment.
On the graph
Hits a ceiling · Throughput, RTT
Where to look
Have the player check remaining data and throttling status in the carrier’s app and run a speed test to see the top speed. On the server side, compare loss and RTT per ISP
Confirmed if
Throughput stops rising at one value such as 1–5 Mbps or a few hundred kbps, and from then on RTT and loss grow whenever other apps on the same phone use data. Goes away after topping up data or switching to Wi-Fi
Ruled out if
No throttling but one ISP is bad: “Peak-hour congestion at peering links” or “Detour routing”
Check with
The player’s own environment
Sources
SKT, 고객 선택권과 혜택 강화한 신규 5G 요금제 출시SK텔레콤 Examples of speed control after a 5G plan’s base data runs out: up to 400 kbps, 1 Mbps, 3 Mbps
SKT, 요금제 개편SK텔레콤 Service continues at up to 400 kbps after the included data runs out (Korea’s nationwide “safety net data” program)