I recently upgraded service from 150up, 10dn Mbps to xfinity's gigabit (with 35Mbps up) tier, and picked up a DOCSIS 3.1 modem to go with it.

Flent test results are here:

https://burntchrome.blogspot.com/2020/03/bufferbloat-with-comcast-gigabit-with.html

tl/dr;  1000ms of upstream bufferbloat

But it's DOCSIS 3.1, so why isn't PIE working?  Theory:  It's in DOCSIS 3.0 upstream mode based on the status LEDs.  Hopefully it will go away if I can convince it to run in DOCSIS 3.1 mode.

At the moment, however, my WRT1900AC isn't up to the task of dealing with these sorts of downstream rates.

So I'm looking at the apu2, which from this post:

https://forum.openwrt.org/t/comparative-throughput-testing-including-nat-sqm-wireguard-and-openvpn/44724

Will certainly get most of the way there.

Although