Upgraded to Gigabit only getting 500/40 trying to troubleshoot

Upgraded from 175mbps yesterday to gigabit. I have an Arris SB8200 (purchased 7/2018) so the modem should be good to go for DOCSIS 3.1 gigabit service. I've done a handful of resets. Eliminated the router (Nighthawk R7000) completely and hardwired a desktop to the modem and have done numerous speed tests from several sources (Xfinity, Ookla, Speakeasy, Google, Fast/Netflix, M-lab) and still only get 500-540 down and 40 up. Even tried in Safe Mode with Networking once to eliminate software.  Followed all the tips in the "Troubleshooting Gigabit Internet Speeds" post/video as well.

Imgur album of modem stats and error log with MAC hidden: https://imgur.com/a/VT5Y8iE

I called this afternoon and the first person I talked to got gruff with me about having my own equipment, that it wasn't Comcast's job to update it, and I needed to call Arris for a software update and then I would get my speed.   This seemed odd, as I've had 2 other personal modems since 2007 and the updates came from Comcast not the manufacturer.  He said because I increased my package 800mbps that's too much for my software.  You must call Arris we can't help you. Looked up Arris and found this relevant Arris FAQ: https://arris.secure.force.com/consumers/articles/General_FAQs/Upgrading-Firmware-on-Cable-Devices

Call back, got the same person, he transferred me to sales when I asked for a modem update. Sales was confused and passed me back to tech support, someone picked up after 20 min and just let it sit for a minute in silence before hanging up.

Call back, got a new person. She said everything looked good on her end for speed, but kept getting a device not supported for 1gig message. (It's definitely on the approved list) She said it had the correct boot file. She ran 3 different tests and I would verify with a speed test that it was still only pulling about 520. At one point it sunk down into the 400s. She was surprised I was getting 40 up though. At one point she said it showed an error icon on my downstream, but she ran that fix and the next speed test was the same and the icon went away. She even waited for me to swap out the cable and still no dice. At this point she said she would set an appointment for a technician visit, but due to covid it was not allowing her to do that. Unsure if it's due to our current local guidelines or if this is too minor of an issue.  She set up a call back for next week to see if it gets better.

Hoping someone here might have some insight with the attached modem data? Maybe my node is overloaded and we didn't know until we bumped up the speed? Ran a speed test after midnight on Thursday/Friday and still didn't improve.