I pay for 15 Mbps down / 1 Mbps up though actual performance seems to be closer to 20/1.5.
Yes - I have Smart Queue turned on for both up and down. Upload is set to 1.2 Mbits/sec and Download is 17 Mbits/sec. I remember following a guide that walked me through setting the values and then iteratively testing and adjusting.
It has been a few months since I turned on the SQM, prior to turning it on I was having Buffer Bloat problems caused by my upstream connection being saturated. Once I turned it on everything started working great.
I replaced my ERL with a new one a couple of weeks ago after the old one was taken out by a lightning strike. I restored the config from the old router to the new one. The old one was running the previous version of Edge OS whereas I have 1.9.0 on the new one. I noticed this problem twice in the last week, I don't recall it happening before (though its very possible I just never noticed).