Slow Upload Speeds

[mjm54]

My download speeds are consistently in excess of 200mbps, but my upload speeds are consistently in thr 1.5-2 mbps range. Is this likely an Xfinity issue or an issue with my equipment?

[BruceW]

Are you connecting via Wifi or Ethernet? If Wifi, it's best to switch to an Ethernet cable connection if possible. That would allow you to determine whether the problem is the Wifi signal or the link between your modem or gateway and Comcast's network. Network connection problems that affect both Ethernet and Wifi devices are often due to poor coax connections or damaged coax cable, usually in or near your home.

If you want to troubleshoot this yourself, please see Internet Troubleshooting Tips. If you still need help, please post your Internet plan speed and the following information from your modem or gateway:

• model number
• downstream power levels and SNR
• upstream power levels
• event log

[mjm54]

Performance Pro+ Internet - 200/5
iMac is hard-wired to Nest WiFi, which is hard-wired to modem.
Modem: MOTOROLA 16x4 Cable Modem, Model MB7420, 686 Mbps DOCSIS 3.0

Downstream info:

Channel	Lock Status	Modulation	Channel ID	Freq. (MHz)	Pwr (dBmV)	SNR (dB)	Corrected	Uncorrected
1	Locked	QAM256	20	525.0	-14.0	33.5	0	0
2	Locked	QAM256	8	453.0	-13.5	33.8	0	0
3	Locked	QAM256	9	459.0	-13.4	33.7	348	878
4	Locked	QAM256	10	465.0	-14.0	33.6	0	0
5	Locked	QAM256	11	471.0	-13.7	34.0	0	0
6	Locked	QAM256	12	477.0	-13.8	34.0	0	0
7	Locked	QAM256	13	483.0	-14.0	34.0	0	0
8	Locked	QAM256	14	489.0	-13.4	34.3	0	0
9	Locked	QAM256	15	495.0	-14.0	34.2	0	0
10	Locked	QAM256	16	501.0	-14.2	33.7	0	0
11	Locked	QAM256	17	507.0	-13.8	32.0	0	0
12	Locked	QAM256	18	513.0	-14.2	33.2	0	0
13	Locked	QAM256	19	519.0	-14.2	32.7	0	0
14	Locked	QAM256	21	531.0	-14.7	33.2	0	0
15	Locked	QAM256	22	537.0	-14.8	32.4	0	0
16	Locked	QAM256	23	543.0	-15.0	32.9	0	0
Total							348	878

Upstream Info:

Channel	Lock Status	Channel Type	Channel ID	Symb. Rate (Ksym/sec)	Freq. (MHz)	Pwr (dBmV)
1	Locked	ATDMA	4	5120	35.6	46.5
2	Locked	ATDMA	1	5120	16.4	49.0
3	Locked	ATDMA	3	5120	29.2	47.0
4	Locked	ATDMA	2	5120	22.8	46.8

Most recent event log entries (most recent prior to these dated 11/9/2020). I suspect the 12:28 entry was when I unplugged the modem & plugged it back in to see if that would help.

Tue Feb 09 12:28:40 2021	Critical (3)	Resetting the cable modem due to docsDevResetNow
Time Not Established	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=00:40:36:43:a3:b0;CMTS-MAC=00:01:5c:9e:54:5a;CM-QOS=1.0;CM-VER=3.0;
Time Not Established	Notice (6)	Honoring MDD; IP provisioning mode = IPv6

[BruceW]

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@mjm54 wrote: Performance Pro+ Internet - 200/5 ... MOTOROLA 16x4 Cable Modem, Model MB7420 ...

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"docsDevResetNow" is a restart command from Comcast to the modem, sometimes initiated by them, sometimes by you using the "reboot" function in the My Account app or web pages. Also, be aware that Comcast rates the MB7420 only for speeds "Up to 374 Mbps", not 686 (see https://www.xfinity.com/support/devices/).

The downstream power levels and SNR are out of spec (too low), and at least one upstream channel is borderline too high. Note that there are other readings that we don't have access to because the modem doesn't report them.

If you can't find the problem or you'd rather have Comcast take care of it, call them at the phone number on your bill or 1-800-Comcast, or use one of the options on https://www.xfinity.com/support/contact-us/. It's not likely they can fix the problem remotely. If not, insist they send a tech out to identify the cause and correct it.

If the tech finds bad coax, splitters, amplifiers, or connections in your home (even if Comcast originally supplied them) you'll probably have to pay for the visit unless you have their Service Protection Plan (https://www.xfinity.com/support/articles/service-protection-plan, closed to customers that don't already have it). If the trouble is due to a faulty Comcast rental device or anything outside your home you shouldn't be charged.

[mjm54]

Thanks for the information. I'm going to check the coax cable when I get a chance. It was in the house when we moved in nearly 3 years ago and the outlet has been behind a large bookcase since then. It's a quite different coax outlet than any I've seen before. There's a rather large white box with a few inches of cable protruding from it that has a longer coax cable attached to it, that is then attached to the modem. The cable attached to the modem will be easy to replace but I'm not sure about the cable coming from that wall-mounted box.

 

[mjm54]

I replaced the unnecessarily long cable left by the previous owner and reset both the modem and the Nest Wifi, and speedtest indicates an upload speed of 3.97mbps, twice as fast as previously.

Thanks again for your input.