Very interesting. I've never been able to test BRAS before as presumably Zen do not use it due to using LLU?
My new Plusnet line is curious though at:
The current Downstream BRAS rate is: 58.62 Mbps (63.5Mbit sync)
The current Upstream BRAS rate is: 20 Mbps
It certainly explains why I got a good bufferbloat score even without QoS.
That seems rather excessively capped considering my Zen line can do 65Mbit with an around 70Mbit sync. (can't get specifics as its current on an ECI modem) Clearly the profile doesn't need to be this low but sounds like its pretty normal for BRAS to be rather overly aggressive.
Its curious that my worst performing line actually has a higher handback threshold than the better performing one. Perhaps because its a brand new line so set to defaults?
I should have a more interesting picture once I switch to Zyxel VMG3925-B10B for the modems.
It does suggest going with an ISP that uses LLU can squeeze a bit more speed out of your line though.