Wi-Fi → WAN upload collapses to 30-50 Mbps without IntelliQoS (KN-1812, KeeneticOS 5.0.7)

[Dmytro Bezkrovnyi]

Wi-Fi → WAN upload collapses to 30-50 Mbps without IntelliQoS (KN-1812, KeeneticOS 5.0.7)

ENVIRONMENT

Router: Keenetic Titan KN-1812, KeeneticOS 5.00.C.7.0-0
ISP: Magyar Telekom, fiber GPON, 1 Gbps symmetric
Topology: MBP (Wi-Fi 6) → Keenetic → Magenta Box (Technicolor FGA2235, DMZ mode) → ISP
Wi-Fi client: MacBook Pro M1 Max (BCM4387), 5 GHz, 2SS/80MHz, 802.11ax
MBP is the only client on 5 GHz band
IntelliQoS config when enabled: CAKE, input 890 Mbps, output 500 Mbps

PROBLEM

When IntelliQoS is disabled (no qos), Wi-Fi upload through WAN drops to 30-50 Mbps. With IntelliQoS enabled (CAKE, output 500 Mbps), upload is stable at ~480 Mbps.

I would expect that removing the 500 Mbps shaper would increase or maintain upload speed, not collapse it by 10x.

DIAGNOSTIC RESULTS

Upload throughput (same iperf3 server, same time of day):

Pi-hole, Ethernet → Keenetic → WAN, QoS OFF:       846 Mbps
MBP, Wi-Fi 5GHz → Keenetic → WAN, QoS OFF:         23-51 Mbps
MBP, Wi-Fi 5GHz → Keenetic → WAN, QoS ON (500):    480 Mbps
MBP, Wi-Fi 5GHz → Keenetic → LAN (iperf3), QoS OFF: 595 Mbps
MBP, Wi-Fi 5GHz → Magenta Box Wi-Fi → WAN, QoS OFF: 610 Mbps
Desktop, Ethernet → Keenetic → WAN, QoS OFF:        450-640 Mbps
Desktop, Ethernet → Magenta Box directly, QoS OFF:  980 Mbps

Key observations:
1. Wi-Fi LAN throughput = 595 Mbps (iperf3) — Wi-Fi radio works fine
2. Ethernet upload through same WAN path = 846 Mbps — WAN path works fine
3. MBP on Magenta Box Wi-Fi directly = 610 Mbps — MBP Wi-Fi chip works fine
4. PHY rate during test: TX 1201, RX 960-1080 Mbps, RSSI -67...-69 — stable
5. WAN interface stats: 0 txdropped, 0 txerrors
6. Problem is specific to Wi-Fi → WAN forwarding without CAKE

What I tested (none helped):
- Disabled hardware PPE (no ppe hardware) — upload still 44 Mbps
- Disabled TSO on MBP (sysctl net.inet.tcp.tso=0) — upload still 45 Mbps

QUESTION

Is this expected behavior? It appears that the default queueing on the WAN egress path cannot handle Wi-Fi-originated traffic properly. CAKE fixes it, but requires an artificial bandwidth limit (500 Mbps) which caps upload below ISP capacity (980 Mbps).

Is there a way to enable CAKE/fq_codel without bandwidth limiting? Or another setting to fix Wi-Fi → WAN forwarding without IntelliQoS?
 

Edited 14 hours ago by Dmytro Bezkrovnyi
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