Extremely slow upload speed (0.5 Mbps) and some T3 time-out error logs.

[sumash]

My home internet started to experience slowness when on videoconference or uploading pic/files about a week ago.  The download speed is normal though. An agent from Xfinity came to my house and checked the signal. He ruled out the problems from cables, and said the upstream power is too low (< 45dBmV), and suggested me to upgrade my modem (Arris sb6183). I then got the new one (SB8200) and still got the same low upload speed issue. So I don't think the problem is the modem. I have spoken to at least 3 specialists and all of them have no idea what's going on. The only useful info I heard is all said they receive no or weak signals from my apartment. 

Here are some upstream info.

Upstream Bonded Channels

Channel	Channel ID	Lock Status	US Channel Type	Frequency	Width	Power
1	3	Locked	SC-QAM Upstream	30300000 Hz	6400000 Hz	43.0 dBmV
2	1	Locked	SC-QAM Upstream	17300000 Hz	6400000 Hz	43.0 dBmV
3	2	Locked	SC-QAM Upstream	23700000 Hz	6400000 Hz	43.0 dBmV
4	4	Locked	SC-QAM Upstream	36700000 Hz	6400000 Hz	43.0 dBmV

[CCAndrew]

There’s a difference between upstream power signal levels, which you posted, and upload speeds which you didn’t post. Your levels posted are in spec. You didn’t post what your actual speeds are and what you’re expecting paying for. Did you do a speed test? Your title thread mentioned it and logs but never posted, or the downstream levels. Are you checking from your modem or from your router?

[sumash]

[sumash]

Sorry, here is more info

plan: 300/10 Mbps

download speed: 263 mbps,  upload: 0.4 mbps, latency: 63 ms, and protocal: Ipv4

Downstream Bonded Channels

Channel ID	Lock Status	Modulation	Frequency	Power	SNR/MER	Corrected	Uncorrectables
20	Locked	QAM256	525000000 Hz	-1.5 dBmV	38.6 dB	5082	11172
17	Locked	QAM256	507000000 Hz	-0.8 dBmV	38.4 dB	4536	12298
18	Locked	QAM256	513000000 Hz	-1.0 dBmV	38.8 dB	4650	11319
19	Locked	QAM256	519000000 Hz	-1.9 dBmV	37.9 dB	4625	10744
21	Locked	QAM256	531000000 Hz	-2.5 dBmV	38.4 dB	5295	11430
22	Locked	QAM256	537000000 Hz	-0.8 dBmV	38.7 dB	5958	11796
23	Locked	QAM256	543000000 Hz	-2.5 dBmV	37.9 dB	6426	11970
24	Locked	QAM256	549000000 Hz	-0.5 dBmV	39.1 dB	6297	11767
25	Locked	QAM256	555000000 Hz	-1.6 dBmV	39.2 dB	7530	11812
26	Locked	QAM256	561000000 Hz	-0.7 dBmV	38.5 dB	8550	11577
27	Locked	QAM256	567000000 Hz	-0.9 dBmV	38.2 dB	9320	11499
28	Locked	QAM256	573000000 Hz	-1.0 dBmV	38.9 dB	9957	11179
29	Locked	QAM256	579000000 Hz	-1.3 dBmV	39.0 dB	10477	11136
30	Locked	QAM256	585000000 Hz	-1.3 dBmV	38.4 dB	11243	10683
31	Locked	QAM256	591000000 Hz	-2.3 dBmV	38.6 dB	11583	11481
32	Locked	QAM256	597000000 Hz	-1.9 dBmV	38.7 dB	11626	12384
33	Locked	QAM256	603000000 Hz	-3.6 dBmV	38.0 dB	11418	13503
34	Locked	QAM256	609000000 Hz	-2.7 dBmV	38.5 dB	11440	13802
35	Locked	QAM256	615000000 Hz	-4.4 dBmV	37.9 dB	11295	14521
36	Locked	QAM256	621000000 Hz	-3.2 dBmV	38.2 dB	10981	15853
37	Locked	QAM256	627000000 Hz	-4.4 dBmV	37.6 dB	10043	17998
38	Locked	QAM256	633000000 Hz	-4.4 dBmV	37.7 dB	9721	19223
39	Locked	QAM256	639000000 Hz	-5.4 dBmV	37.5 dB	9358	20593
40	Locked	QAM256	645000000 Hz	-6.0 dBmV	37.4 dB	8934	19936
41	Locked	QAM256	651000000 Hz	-5.3 dBmV	37.8 dB	8637	18466
42	Locked	QAM256	657000000 Hz	-5.4 dBmV	37.5 dB	8576	17609
43	Locked	QAM256	663000000 Hz	-4.4 dBmV	37.8 dB	8579	18762
44	Locked	QAM256	669000000 Hz	-5.7 dBmV	37.3 dB	2925	9644
45	Locked	QAM256	675000000 Hz	-5.4 dBmV	36.6 dB	8074	20311
46	Locked	QAM256	681000000 Hz	-7.0 dBmV	36.8 dB	7902	19928
47	Locked	QAM256	687000000 Hz	-7.3 dBmV	36.7 dB	817	2649
48	Locked	Other	850000000 Hz	-4.2 dBmV	35.8 dB	1558750738	8384

Upstream Bonded Channels

Channel	Channel ID	Lock Status	US Channel Type	Frequency	Width	Power
1	3	Locked	SC-QAM Upstream	30300000 Hz	6400000 Hz	43.0 dBmV
2	1	Locked	SC-QAM Upstream	17300000 Hz	6400000 Hz	43.0 dBmV
3	2	Locked	SC-QAM Upstream	23700000 Hz	6400000 Hz	43.0 dBmV
4	4	Locked	SC-QAM Upstream	36700000 Hz	6400000 Hz	43.0 dBmV

10/18/2020 14:09	82000500	3	"Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;"
10/18/2020 14:02	74010100	6	"CM-STATUS message sent. Event Type Code: 24; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.;CM-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;"
10/18/2020 14:02	74010100	6	"CM-STATUS message sent. Event Type Code: 16; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;"
10/18/2020 14:00	82000500	3	"Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=xxx;CM-QOS=1.1;CM-VER=3.1;"

[Snic8]

I was having the extact same problem with tons of uncorrectables on all of my channels. Comcast replaced the line coming into my house and now I only have errors on channel 48. This past week, it has been really bad. The internet is so intermittent that it's borderline unuseable. I am using the SB8200. I contact comcast and they say that it's a modem problem. I contact Arris and they say that it's a comcast problem.

Startup Procedure

Procedure	Status	Comment
Acquire Downstream Channel	525000000 Hz	Locked
Connectivity State	OK	Operational
Boot State	OK	Operational
Configuration File	OK
Security	Enabled	BPI+
DOCSIS Network Access Enabled	Allowed

Downstream Bonded Channels

Channel ID	Lock Status	Modulation	Frequency	Power	SNR/MER	Corrected	Uncorrectables
20	Locked	QAM256	525000000 Hz	7.0 dBmV	41.2 dB	0	0
17	Locked	QAM256	507000000 Hz	6.7 dBmV	41.1 dB	0	0
18	Locked	QAM256	513000000 Hz	6.4 dBmV	41.0 dB	0	0
19	Locked	QAM256	519000000 Hz	6.4 dBmV	41.0 dB	0	0
21	Locked	QAM256	531000000 Hz	7.1 dBmV	41.2 dB	0	0
22	Locked	QAM256	537000000 Hz	7.0 dBmV	41.3 dB	0	0
23	Locked	QAM256	543000000 Hz	7.2 dBmV	41.2 dB	0	0
24	Locked	QAM256	549000000 Hz	7.8 dBmV	41.4 dB	0	0
25	Locked	QAM256	555000000 Hz	7.5 dBmV	41.3 dB	0	0
26	Locked	QAM256	561000000 Hz	7.6 dBmV	41.3 dB	0	0
27	Locked	QAM256	567000000 Hz	7.9 dBmV	41.3 dB	0	0
28	Locked	QAM256	573000000 Hz	7.9 dBmV	41.4 dB	0	0
29	Locked	QAM256	579000000 Hz	7.7 dBmV	41.2 dB	0	0
30	Locked	QAM256	585000000 Hz	8.0 dBmV	41.2 dB	0	0
31	Locked	QAM256	591000000 Hz	8.4 dBmV	41.5 dB	0	0
32	Locked	QAM256	597000000 Hz	8.3 dBmV	41.3 dB	0	0
33	Locked	QAM256	603000000 Hz	8.3 dBmV	41.3 dB	0	0
34	Locked	QAM256	609000000 Hz	8.5 dBmV	41.4 dB	0	0
35	Locked	QAM256	615000000 Hz	8.6 dBmV	41.3 dB	0	0
36	Locked	QAM256	621000000 Hz	8.5 dBmV	41.4 dB	0	0
37	Locked	QAM256	627000000 Hz	8.7 dBmV	41.3 dB	0	0
38	Locked	QAM256	633000000 Hz	8.9 dBmV	41.5 dB	0	0
39	Locked	QAM256	639000000 Hz	8.7 dBmV	41.4 dB	0	0
40	Locked	QAM256	645000000 Hz	8.8 dBmV	41.5 dB	0	0
41	Locked	QAM256	651000000 Hz	8.9 dBmV	41.5 dB	0	0
42	Locked	QAM256	657000000 Hz	9.1 dBmV	41.7 dB	0	0
43	Locked	QAM256	663000000 Hz	8.9 dBmV	41.5 dB	0	0
44	Locked	QAM256	669000000 Hz	8.8 dBmV	41.6 dB	15	0
45	Locked	QAM256	675000000 Hz	9.2 dBmV	41.5 dB	0	0
46	Locked	QAM256	681000000 Hz	8.6 dBmV	41.5 dB	0	0
47	Locked	QAM256	687000000 Hz	8.9 dBmV	41.7 dB	0	0
48	Locked	Other	850000000 Hz	7.2 dBmV	39.5 dB	621900572	0

Upstream Bonded Channels

Channel	Channel ID	Lock Status	US Channel Type	Frequency	Width	Power
1	3	Locked	SC-QAM Upstream	30300000 Hz	6400000 Hz	44.0 dBmV
2	1	Locked	SC-QAM Upstream	17300000 Hz	6400000 Hz	45.0 dBmV
3	5	Locked	SC-QAM Upstream	41200000 Hz	1600000 Hz	43.0 dBmV
4	2	Locked	SC-QAM Upstream	23700000 Hz	6400000 Hz	45.0 dBmV
5	4	Locked	SC-QAM Upstream	36700000 Hz	6400000 Hz	44.0 dBmV

[sumash]

Thanks for the information. That's very useful. Do you still have the same problem after they replaced the line to your house?  I have seen other people's log also shows channel 48 having lots of errors (It seems to be normal though I don't know why)

The following was what I experienced as well. 

---

@Snic8 wrote:

I contact comcast and they say that it's a modem problem. I contact Arris and they say that it's a comcast problem.

Another tech came yesterday and did a full diagnosis on all possible causes, and concluded it's Xfinity's problem (in the box outside my apartment).  They are sending someone to fix it. 

[sumash]

The last agent said they will fix it in 3 days.  Still, no response from Xfinity and the internet cannot be worse, with a few outages in the past few days.  really disappointed.