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We are using a wifi-enabled device that receives a stream of UDP packets (30 per second). It is very important for us to receive these messages without lag, that's why we are using UDP and not TCP connections.

We notice that after some time many routers will start buffering these packets, creating a noticeable delay. When such routers are rebooted, the delay ceases, and starts building over time again.

We found out one router that have these settings that when deactivating them the lagging disappears:

  • Wifi Professional Settings:
    • Enable TX Bursting: Disable
    • Enable Packet Aggregation: Disable

Is this something usual? I suspect that we are doing something wrong because other UDP applications don't have this type of problem. Is there any way I can force routers that don't expose this settings to not buffer UDP messages and just drop the ones that they can't deliver, by changing something in the protocol?

I'll appreciate any directions on how to learn more about this issue.

Thanks!

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  • What type of router do you mean (model)? – Ron Maupin Oct 10 '19 at 13:15
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If you need to reduce latency and guarantee in-time delivery you need to use wired Ethernet.

With Wi-Fi there's no guarantee for any timely delivery. Wireless frames compete for air time and can be delayed by congestion or radio interference. Since we're at the data link layer here (L2), the transported network-layer and transport-layer protocols don't matter at all. So, there's no difference for UDP or TCP packets.

Some WAPs may support L4-based QoS (to drop UDP frames more quickly on congestion) but that's not standard. Please add your device details (model & sanitized config) to your question, perhaps anyone here can help you then. Note that only business-grade hardware with optional paid support is on-topic here.

Disabling bursting and other radio optimizations effectively use up more air time and cause more congestion. If a device works better that way that's not a good sign for its overall quality.

Generally, to get away with wireless you'd need to optimize your Wi-Fi segment for maximum throughput (drop legacy 802.11 modes, remove distant nodes, move APs & clients closer together, select least congested channel(s), rule out/remove other sources of interference, ...).

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