How to work around saturating VDSL connection.

I got feedback from users of my home network that when uploading big files, the connection gets really slow and nothing works. We have a VDSL connection which has significantly slower upstream compared to downstream.

To debug this I set up a test where I ping a host in the internet side while doing a speedtest. When speedtest was doing the upload test, ping jumped from normal 20-30ms level to 1000ms level. As soon as uploading stopped, ping returned back to normal. When uploading at maximum speed, the upload bandwith is saturated and all other connections, including download is cripled.

I use OpenWRT in my intranet router and it supports feature called SQM (Smart Queue Management) which allows to set bandwidth limits. After setting that up and re-testing, all was well again. Ping times fluctuate a bit in both download and upload tests but still stay well under 60ms. Practical upload speed did not drop and the connection is usable all the time.

Great Success :)