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Fix bufferbloat on Ubiquiti UniFi routers

Real Smart Queue

Yes. UniFi gateways have Smart Queues, which is real Smart Queue using fq_codel.

Smart Queues limits your line to the speeds you set and uses fq_codel so small packets don't wait behind big transfers.

1. Test before you change anything

Run the Lag Check and note the "Lag under load" grade and your download and upload speeds. You'll compare against it afterwards.

2. Where the setting is

UniFi Network

  1. In UniFi Network, go to Settings → Internet and select your WAN.
  2. Turn on Smart Queues and enter your download and upload limits.
  3. Apply, then test again. The exact placement moves between UniFi Network versions; older versions keep it on the WAN network's settings.

3. The numbers to enter

UniFi asks for Mbps. Start at about 90% of your measured speed, or use the figures from the Smart Queue assistant.

Work out my limits

The assistant starts at 90% of your measured speed and tells you when to drop to 85% or 80%.

Gotchas

  • On many gateways Smart Queues turns off hardware offloading, so the gateway's CPU does the work. Older and smaller gateways are only suited to lines of a few hundred Mbps with it on; above that, check the shaped speed.
  • If you have more than one WAN, set it on the one you use.

Test after the change. A good setup brings lag under load down to A or B.

Test before and after