Mediacom owned Netgear CM1000 has recent Very Slow Upload

[Anthony_Heman]

I've had this modem for since October 2017 and it  has done the job well up until about a month ago. Download speeds are all still great (130 megs, paying for 100), but upload is miserable... mostly at night (0.1 megs). During the day it might get as high as 5. The weather has been cold, and people are home a lot more, I'm not sure if any of that could matter. Technical support was convinced it was the modem, but they didn't ask me for any information from it like power, which I see mentioned a lot here. Well I decided to order a new CM2000, not that I need the speeds that offers, partially because I wanted to be able to test it myself, but I was curious if there was anything discernable from the status page that someone might consider an obvious problem.

For testing I've isolated the modem to directly connect to my desktop PC and get the same speed results. I've also tried going off the wifi in a separate test (since that goes through a different cable just to rule out eithernet... I guess) and got the same results.

I think I'm using the best coax I have access to in my apartment, but I'm not positive. It's the only one I see that makes sense as where "it comes into the apartment." Other rooms are wired up however, but nothing about that should have changed (and I don't actually use the coax for anything but this cable modem).

Hardware Version 2.02

Firmware Version V3.01.04

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR / MER	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	QAM256	1	111000000 Hz	7.4 dBmV	42.4 dB	31230864	0	0
2	Locked	QAM256	2	117000000 Hz	7.1 dBmV	42.6 dB	31253070	0	0
3	Locked	QAM256	3	123000000 Hz	6.8 dBmV	42.5 dB	31261578	0	0
4	Locked	QAM256	4	129000000 Hz	7.6 dBmV	42.8 dB	31270789	0	0
5	Locked	QAM256	5	147000000 Hz	7.9 dBmV	43.1 dB	31279749	0	0
6	Locked	QAM256	6	153000000 Hz	8.1 dBmV	43.3 dB	31289149	0	0
7	Locked	QAM256	7	159000000 Hz	8.2 dBmV	43.3 dB	31298364	0	0
8	Locked	QAM256	8	165000000 Hz	8.3 dBmV	43.3 dB	31307916	0	0
9	Locked	QAM256	9	171000000 Hz	8.4 dBmV	43.2 dB	31320764	0	0
10	Locked	QAM256	10	177000000 Hz	8.3 dBmV	43.0 dB	31329855	0	0
11	Locked	QAM256	11	183000000 Hz	8.5 dBmV	43.3 dB	31339137	0	0
12	Locked	QAM256	12	189000000 Hz	8.2 dBmV	43.2 dB	31348533	0	0
13	Locked	QAM256	13	195000000 Hz	8.2 dBmV	43.0 dB	31357898	0	0
14	Locked	QAM256	14	201000000 Hz	8.4 dBmV	43.2 dB	31367639	0	0
15	Locked	QAM256	15	207000000 Hz	8.5 dBmV	43.2 dB	31374043	0	0
16	Locked	QAM256	16	213000000 Hz	8.5 dBmV	40.2 dB	31378948	1	0
17	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
18	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
19	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
20	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
21	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
22	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
23	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
24	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
25	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
26	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
27	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
28	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
29	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
30	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
31	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0
32	Not Locked	Unknown	0	0 Hz	0.0 dBmV	0.0 dB	0	0	0

Upstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power
1	Locked	ATDMA	1	36500000 Hz	26.0 dBmV
2	Locked	ATDMA	2	29750000 Hz	26.0 dBmV
3	Locked	ATDMA	3	22750000 Hz	24.8 dBmV
4	Not Locked	Unknown	0	0 Hz	0.0 dBmV
5	Not Locked	Unknown	0	0 Hz	0.0 dBmV
6	Not Locked	Unknown	0	0 Hz	0.0 dBmV
7	Not Locked	Unknown	0	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Hz	0.0 dBmV

Downstream OFDM Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power	SNR / MER	Active Subcarrier Number Range	Unerrored Codewords	Correctable Codewords	Uncorrectable Codewords
1	Locked	0, 1, 2	200	309000000 Hz	8.7 dBmV	40.3 dB	148 ~ 3947	12247944	2910230	0
2	Not Locked	0	0	0 Hz	8.4 dBmV	0.0 dB	0 ~ 4095	0	0	0

Upstream OFDMA Channels

Channel	Lock Status	Modulation / Profile ID	Channel ID	Frequency	Power
1	Not Locked	Unknown	0	0 Hz	0 dBmV
2	Not Locked	Unknown	0	0 Hz	0 dBmV

[plemans · Accepted solution]

Not all of your downstream channels are locked and your upstream power is really low. You should be 35+ on the upstream. you're at 26. 

Your logs would tell us more but it indicates a line issue at this point. 

If your isp is saying "its not our lines, its the 3rd party modem" and won't fix it, I've had to actually rent a modem before to prove it was a line issue. Once its fixed, I simply returned the modem and put mine back in. 

[plemans · Accepted solution]

Not all of your downstream channels are locked and your upstream power is really low. You should be 35+ on the upstream. you're at 26. 

Your logs would tell us more but it indicates a line issue at this point. 

If your isp is saying "its not our lines, its the 3rd party modem" and won't fix it, I've had to actually rent a modem before to prove it was a line issue. Once its fixed, I simply returned the modem and put mine back in. 

[Anthony_Heman]

Interestingly I was able to kinda take your words and the lines from my stats page and get them to send out a tech... it won't be for a week, but that's better than getting the new modem, trying it out, seeing that it doesn't solve the problem and then waiting another full week after that.