Background: Had one of the old Arris Comcast modems for quite a while. They sent me a new one but I thought I'd just get a better cable modem and upgrade for Gigabit capability. So I got a Netgear CM 1200.
The house is new construction (less than 3 years old) and Comcast installed the first drop from the pole to the house. We have multiple outlets in multiple rooms, but we don't use cable TV and the Comcast tech only connected the coax to the room we're using as he said unused outlets acted like antennas and contributed to signal degradation.
Switching to the new modem brought trouble. Random disconnects every few days. They've increased in frequency and now I'm getting consistent 20-50% packet loss.
The modem is throwing multiple errors in the log.
"Started Unicast Maintenance Ranging - No Response received - T3 time-out;"
"REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;"
"Notice (6) TLV-11 - unrecognized OID;"
"Warning (5) REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;"
My upstream signal levels are at 48.5dBmV which seems high. My downstream are between 4.5dbmV and 8dBmV. No uncorrectables but a reasonable amount of correctables. My signal to noise ratio is between 8 and 9dB.
The modem is connected directly to the wall. No splitter.
I tried a Comcast chat agent to try and get a tech out to check the line, but they asked a bunch of questions, issued a "signal refresh" then told me if the problem doesn't fix itself, then it's my modem. This seems unlikely.
Does anyone have any idea how I can get this sorted? Comcast support doesn't seem like the route to go. And can anyone knowledgable comment on my modem signal levels?
Any help greatly appreciated. I'm frustrated and have no idea how I can get Comcast to take this seriously.
Sorry, the SNR is between 38 and 39. Not sure where my head was at.
Reading through the forums, the impression I get is that this issue is widespread and it seems to come down to the modem's inability to make itself heard by the CMTS. I've read the normal upstream power should be around 35-45 dBmV and mine is at 48 and higher as follows:
|Channel||Lock Status||US Channel Type||Channel ID||Symbol Rate||Frequency||Power|
|1||Locked||ATDMA||1||5120 Ksym/sec||36500000 Hz||48.3 dBmV|
|2||Locked||ATDMA||2||5120 Ksym/sec||30100000 Hz||49 dBmV|
|3||Locked||ATDMA||3||5120 Ksym/sec||23700000 Hz||48.5 dBmV|
|4||Locked||ATDMA||4||5120 Ksym/sec||17300000 Hz||48.5 dBmV|
Point is, I've seen other folks manage to get a tech out to take a look at the signal levels and I want to try and understand how I can get that done. I don't mind taking the modem back provided I have some hard evidence, however Comcast's attitude that this is not their problem is odd given how many people are having this exact same issue.
The upstream power is on the high side and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
You should get a tech out to properly balance the line. Good luck !
I'd love to get a tech out, but I have no idea how to do this. I tried specifically asking for one from the chat agent, but they ran through a bunch of diagnostics then told me the problem was with my modem and abruptly disconnected the chat. They clearly didn't want to spend any more time on this.