Comcast XFINITY → [Equip] Does this explain why my speeds are so slow?

Xfinity did some upgrading in the area. When the lights came back on, they really bumped the speed on the old DOCSIS 3.0 modem, pretty much to the limit it could handle. I got excited and on a lark found I was eligible for up to 1Gb service. (W00t!) For $10 more than what I was already paying for, I could get 600Mb/20Mb and started the checkout procedure. I failed the modem check before you purchase, it was just too outdated. I found a great deal at local store for an Arris SB8200.

The walled garden is no more, you have to use the Xfinity App from a smart phone to get the modem up and installed. That took 5 minutes, no biggie. I got all excited again and boosted up to the 600Mb/20mb plan. I check out my cart, get my confirmation e-mail and the SB8200 reboots. Once back online I did a direct wired speed test via gigabit Ethernet and a brand new CAT6e cable aaaaannnnnnndddd.....

My upstream is dead on fast @20Mb, the download, not so much. The best it pulls is 50% of my 600Mb speed tier. I go nosing in the modem's event log and find these lines you see above.

*Thinking* it's a provisioning problem, I give Xfinity a call. They can't figure it out, had to authorize overrides, but ultimately had a great cozy chat with 2 lvl-3 techs and appointments for two truck rolls. One for the plant management, the other for a house tech to come investigate the stuff around/in the house.

Color me stupid, but am I off the mark by thinking this is a provisioning problem? The two techs attempted to re-provision twice, and it wouldn't stick. I'm not convinced a truck roll will do it. What say you all?

Here you go. I think they look in spec...what do I know?

EDIT: The one downstream OFDM channel that's pushed to the far end of my sub-600MHz system has error counts that just keep rising and rising now - that I bothered to look. Between that and failed software download, I'm starting to think is my problem.