Gigabit x2 Tier: Stuck at 72 Mbps Upload / Missing Upstream OFDMA Channel / High Downstream Correctable Codewords on XB8
I recently upgraded to the Gigabit x2 speed tier. While my download speed is absolutely perfect (hitting 2100 Mbps downstream over my Archer BE550 and when I was plugged into the XB8), my upload speed is hard-capped at exactly ~72 Mbps.
On this plan, I should be seeing the enhanced 200–300 Mbps upload mid-split speeds.
I pulled my local gateway diagnostics from the 10.0.0.1 admin page on my XB8 (currently running successfully in Bridge Mode), and the problem is explicitly clear in the DOCSIS signal tables:
- Missing OFDMA Upstream: The gateway is completely failing to bond to any OFDMA upstream channels. It is locked entirely onto four legacy ATDMA channels capped between 16 MHz and 35 MHz.
- High Downstream Noise/Errors: On the downstream side, Channel 4 and Channel 193 (OFDM) are accumulating massive errors, showing over 16.4 million correctable codewords within a very short window after a reboot. (Uncorrectables are currently at 0, so the hardware is brute-forcing the download, but the line is incredibly noisy).
Because my download speeds are maxing out the tier profile, I know the routing layout is fine. The issue is either a backend billing/provisioning profile error failing to push the mid-split bootfile to my gateway, or severe ingress noise on my physical drop/street tap that is blocking the high-frequency return path needed for OFDMA to lock.
Software Version: CGM4981COM_8.2p7s1_PROD_sey
I have already done all the troubleshooting I can. Plugging into the unit itself, factory reset, 30s+ power cycles, signal refresh, etc.
Thank you! (I used AI to help summarize the last 4 hours of my life trying to get this working correctly).