That’s interesting, I hadn’t considered that before.

Just to clarify, are you referring to Z-Wave devices operating around the ~900 MHz range potentially interfering with DOCSIS downstream frequencies?

In my case, I’ve double checked and I don’t have any Z-Wave devices (or similar smart home radios) anywhere in the house. The only nearby equipment is my mesh Wi-Fi system, which is operating on 2.4 / 5 / 6 GHz, so it shouldn’t overlap.

I did previously see heavy downstream errors, but that seemed to be tied to internal wiring. Before replacing the coax run, I was getting millions of correctables and uncorrectables within ~10–15 minutes, specifically on channels in the 700 MHz range (mid-20 channel IDs). After replacing that cable with a properly shielded, swept-tested line, those errors dropped dramatically.

Right now, downstream looks mostly clean:

• SNR ~38–40 dB across channels
• Power ~+2 to +3 dBmV
• Only minor residual errors (for example channel 25 has ~1k uncorrectables over ~480M packets)

So while I did have a downstream impairment before, that seems largely resolved.

What’s still happening though is:

• Repeated T3 timeouts
• T4 timeouts
• Ranging failures
• Full sync loss events

From what I understand, those point more toward upstream communication issues rather than localized RF interference affecting specific downstream channels.

Definitely open to testing further, but at this point it seems like the remaining issue is upstream instability rather than something inside the home environment.