My Comcast HSI 50/10 (no TV or phone) was set up almost a month ago. Single family dwelling, ground block about 30' from the pedestal. Had Comcast TV at this address a few years ago, so I opted for a self install.
Motorola SB6141 purchased new from Amazon.
Firmware Name: SB_KOMODO-1.0.6.10-SCM00-NOSH
Boot Version: PSPU-Boot(25CLK) 1.0.12.18m3
Hardware Version: 7.0
The modem has been rebooting and logging T3 and T4 timeouts. Some days the dropouts are very bad. I have been graphing the data from the modem's web UI, hoping to gain insight. The graphs above are from the best day I have recorded since I began graphing. Most days, the errors are much worse, and the connection frequently becomes unusable. But the power and SNR patterns are typical.
Over the course of a day, US varies from 39-51 dBmv when the modem manages to bond upstream. When it fails to bond, it varies 39-56 dBmv but the connection seems more reliable. DS varies -2 to +7 dBmv, mirror image of the US.
US is usually low at night and high in the day, with gradual changes, but sometimes there are abrupt changes that break that pattern. During those abrupt changes, the modem logs thousands to tens of thousands of correctable and uncorrectable errors, and I see packet loss.
DS SNR hovers around 35-36 following the day/night pattern, with occasional 34 and 37.
I've called Comcast support several times now, and finally got a tech visit scheduled for next Wednesday. I understand the techs have can significant workload, and I'm looking for pointers to get the best results out of the tech visit.
During the last two weeks I've done everything I could think of to eliminate problems on my side of the demarc.
I've pulled an appropriately sized (50') length of brand new RG6, being careful to respect its bend radius. This cable goes directly from the ground block to the back of the modem--no splitters or wall plates.
I tested the quality of the ground at the ground block. It seems fine, very low resistance and no voltage.
I replaced the ground block, because old dielectric from years ago had gotten gummy.
So far it seems like the only thing that makes the connection usable is when the modem fails outright to bond the upstream channels, as in the graphs above. Then I get many hours of stable service, with only occasional bursts of errors and packet loss.
At this point I really think the problem is upstream of my ground block. Does it seem that way to you? Any advice on convincing the tech of this?
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