Persistent plant-side RF issues on Armstrong (Hitron CODA-57) – spectrum void, channel-specific errors, high upstream power, load-dependent spikes. Looking for tech opinions.
I’ve been dealing with this for a long time (20 months) on Armstrong cable (1000/20 plan, currently measuring ~25 Mbps up). New dedicated drop and Hitron CODA-57 modem were installed July 25, 2026. Problems continued on the new line, so this should be past the house.
Main symptoms
- Intermittent ping spikes, jitter, and “network error” messages in multiple online games, during prime time 6-1am on weekends it gets the worse, here is an example screenshot, i literally have hundreds of these for evidence. The graph is just showing the first hop which is Armstrongs network
- I can make clear rhythmic latency spikes appear on demand by putting a steady 6–8 Mbps upstream load on the connection (OBS stream). This is only ~30-40% of available upload.
- Same bitrate was fine for years on Armstrong (even on lower upload tiers) until these modem symptoms started
Pingplotter graphs of what it looks like when streaming, all graphs showing first hop
Modem evidence (still present)
- Persistent deep spectrum void at 555–575 MHz (power drops to –45 to –60 dBmV). Confirmed with both wide scans and the 6 MHz spans the local supervisor requested (centers at 560/565/570/575).
- Notches / spikes in the ~700 MHz region that line up with channels 22 & 23 (705 & 711 MHz)
- Channels 22 & 23 accumilating thousands of uncorrectables while every other channel stayed at zero
- Upstream power sitting in the low-to-mid 50s (Port 2 currently ~51–52 dBmV) with a history of climbing and multiple RNG-RSP power warnings
- Clusters of T3 timeouts and “Unicast Maintenance Ranging attempted – No response – Retries exhausted” events (notable cluster on Aug 9)
What Armstrong has done / said
- New drop + dedicated modem installed (my pc is directly wired into modem)
- Local supervisor and NOC have repeatedly said remote checks and pings to the modem look clean
- They dismissed upstream power >48 dBmV as normal for this modem model
- They have done general level / CLI checks but have not (that I can confirm) done frequency-specific measurements on the void or the 705/711 region
- A “drive-by” / physical inspection of the tap and plant was supposed to happen; still waiting on actual results
The lead supervisor for local office says he has never looked at a modem log and was debating me on every evidence point. (channel 22 being secondary, spectrum void not valid because the span was set to 200 and 30 instead of 6mhz? power level is not that high, t3 timeouts "nothing to worry about") etc. checked the ping to modem while i was streaming and said it looks "perfect" so hes not seeing the spikes? Keeps insinuating the issues is on my end but we have done everything to rule out if the issue is in my home (4 different cables, 4 seperate modems, brand new drop line ran, tested on 3 different pc's, different power strips, even monitored my voltage on my pc incase power fluctuations) Im recording everything for evidence if i have to report to FCC. Here is the most recent call transcript i had with my local supervisor and what was said, used ai to transcribe so there will be errors https://pastebin.com/VYbqMG9v
My question to techs
Does this pattern (persistent spectrum void + notches on specific frequencies, history of channel-specific uncorrectables, elevated/climbing upstream power with warnings, T3s, and clear load-dependent upstream spikes that survive a new drop) look like a classic plant impairment that needs a real line sweep / frequency-specific check and physical inspection of the tap and plant past it? Or is there something else I should be looking at? I have been using AI to help me diagnose this issue and what to say to support and my local supervisor to get them to fix it. Can any tech here tell me what you suggest saying or doing to get this fixed?
Happy to provide more screenshots or clarify anything i have TONS of pingplotter graphs showing peak hours when not even streaming with very bad ping jitter and packet loss. Thanks for any insight.
*edit more info
They have been out here A TON before a tech installed a new separate drop line into the same tap. So right now i have this new line and new modem that is separate from other line and modem my family uses. We have swapped different modems on the other line my family uses multiple times but i think it was just back and forth between the ARRIS CM8200A and hitron coda-57 not sure if they have any other modems they carry, so right now im on the HITRON coda-57 and my family modem is an ARRIS CM8200A, both modems show identical errors (at least that's what AI said) Here is screenshots i took of that modem 2 weeks ago, it has a really long uptime compared to the other modem, i think there are a bunch of uncorrectables because of an outage (should i reset counter and see what i get after?) Here are the screenshots of that modem https://imgur.com/a/HaC83JR
Also they said they found some corrosion somewhere on the line and fixed it like over a month ago so i assume they inspected it all and just found that corrosion on the plant side. They inspected the wires for the old modem and redid some of that as well so im assuming they "fixed" all the obvious problems they found, so they either missed something when they did all that or the problem is further down the line on the plant side of things? All of the inspection has been more than a month ago.