SQM Slows 230Mbps Down to 9 Mbps on Edgerouter X

I've got 18.06.4 (kernel 4.14.131) installed on an Edgerouter X (2 core 4 thread 880 MHz MIPS) running as my home gateway with a DOCSIS 3.0 cable modem on eth0 and wireless AP/switches on the other ports. Without SQM I get ~230/12 up/down and horrendous bufferbloat. I installed luci-app-sqm and set down/up to 200/10, enabled cake, piece of cake script, and link layer set to Ethernet with 22 byte per packet overhead. It solved the buffer bloat problem, but my download speed has dropped to ~9 Mbps and upload is a little lower. CPU is 97% idle during speedtest - doesn't look like I'm running out of horsepower there. The only change (other than SQM) I've made from the default OpenWRT configuration is changing the static IP of the LAN to my private network address. The default configuration includes IPv6 WAN. I installed ethtools and tried turning gro and gso off (suggested in another old thread) - that didn't help either. Any ideas for what I'm doing wrong?

some info w numbers

Yep - I found that one. 200 Mbps and 3ms bufferbloat with software flow offload and SQM. I'm only getting 9 Mbps. Something's not right.

With software flow off load clicked on and no SQM I'm getting 688ms avg bloat lag and 233 Mbps down (CPU drops to ~77% idle); up I'm getting 11.2 Mbps with 84 ms avg. Still a far cry from 200 Mbps, and that's without SQM.

On what interface do you have SQM configured? It sounds like you either configured it on eth0 or the LAN vlan. Make sure you configure it on the WAN interface.

Edit: if you show me a screenshot of the "interfaces" page in Luci I can help you pick the correct interface :slight_smile:

Edit 2: if you have the correct interface selected, your download speed should be entered at ingress, while the upload speed should be entered under egress.

Show a screenshot of your sqm page and interfaces pages if you want me to point out where the error is :wink:

Mushoz, Thank you! I configured SQM on eth0, because port 0 is where I plugged in the cable modem and that's my WAN, right? Wrong. My WAN is configured on eth0.2 (wan, wan6), and when I set SQM to that interface, all is well. Where's that face plant emoji again?

I'm now getting ~183 Mbps down with bufferbloat of ~25ms without software offloading. CPU is ~43% idle -room to spare. Thank you again for pointing me in the right direction!

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