Repeated T3 Timeouts Every ~50 Minutes After Two Tech Visits

Hi there, I’m hoping to get some help with an issue that’s still happening after two technician visits.

I’m continuing to see “No Ranging Response received – T3 time-out” errors, and they occur on a very regular interval of about every ~50 minutes. Here are a few recent examples from 12/21:

• 20:58:12

• 21:47:14

• 22:36:38

During my most recent technician visit, the tech removed a loose 3.5 dB splitter and connected my modem directly to the main coax line (so there are no splitters in the home), and he confirmed the coax readings were in spec on his meter. Even with that, the issue continued with no improvement.

My upstream OFDMA transmit power consistently sits around ~50 dBmV, which I understand is borderline/high for DOCSIS 3.1 and can lead to ranging failures. The T3 timeouts continue, especially in the evening. Before switching to my current Arris G36, I was also experiencing packet loss and instability on the Xfinity-provided modem, so the issue appears unrelated to the modem itself. I’ve also tried two different Ethernet cables.

To test outside of gaming, I also ran multiple pings to Cloudflare’s DNS (1.1.1.1). Most tests were clean, but one test showed around 2% packet loss, including a timeout, and I occasionally see latency jump from ~6 ms up to ~30 ms. The intermittent nature of the loss matches the timing of the T3 errors and further suggests an upstream issue rather than anything inside my home.

Additional info:

• Current modem: Arris G36 (DOCSIS 3.1)

• Downstream power/SNR are normal

• Legacy upstream QAM is normal (~45–46 dBmV)

• Only the OFDMA upstream remains borderline/high (~50 dBmV)

• T3s mainly appear in the evening/night

• Coax line tested good on the technician’s meter

Since two tech visits have already addressed the in-home wiring, the coax tested good, and the problem persists even when connected directly to the main line, I’m wondering if this could be a return-path or node issue outside my home.

If possible, could someone check for upstream noise or any node/plant issues in my area and let me know if this should be escalated to maintenance?

Thank you very much. I really appreciate any help you can provide.