A couple of my clients I host complained in recent days about slow speeds, so I did a speed test to start diagnosing stuff here. Download speed was ever so slightly lower than it used to be, 100-105 vs the old 120-ish mb. Upload was half what it should be and always has been: 9-10mb instead of 20-22. The SMC gateway shows what has been a normal downstream 4 channel/256qam config. The upstream shows 2 64qam channels at 5120 symbol rate, again, seemingly ok. I think there used to be a third 16qam upstream channel. There was recent local construction in which I was given notice of a scheduled outage overnight in the last couple of weeks. Maybe some config got changed or hosed upstream? I called the trouble in Friday night, was told to expect a callback Saturday. No callback or update *sigh*. Crossing my fingers here for good news soon.
Solved! Go to Solution.
Here you go! Thought I'd just post it all.
Downstream Frequency 656.997803 MHz 662.999023 MHz 669.000366 MHz 675.001587 MHz
Lock Status Locked Locked Locked Locked
Modulation 256 QAM 256 QAM 256 QAM 256 QAM
Symbol Rate 5.360537Msym/sec 5.360537Msym/sec 5.360537Msym/sec 5.360537Msym/sec
Downstream Power 5.369305 dBmV 4.919776 dBmV 4.408798 dBmV 4.881545 dBmV
SNR 38.257755 dB 38.257755 dB 38.257755 dB 38.257755 dB
Upstream Frequency 34800206 Hz 20999995 Hz
Lock Status Locked Locked
Modulation 64QAM 64QAM
Symbol Rate 5120 KSym/sec 5120 KSym/sec
Upstream Power 46.0000 dBmV 45.2500 dBmV
Channel ID 81 83
Hey, I'm having a similar problem; except my upload speed is completely in the gutter. I'm getting around 90 Mbps download and maybe 300 Kbps up. I pay for 75/15 if I'm not mistaken.
Those signals look fine, though I would think there would be 3 ustreams, as you said.
To the both of you in this topic, I am assuming you have tried the basics:
-Speed test with a single computer plugged directly into the modem
-Tried a different ethernet cable
-Tried a different computer
-Made sure the computers are gigabit, and that the cable is Cat5e or better
-Power cycled the gateway, and tried doing a factory-reset (be aware that factory resets remove any configured static IPs, and you will have to call in to get them re-applied)
-Made sure that all coax cable connections are tightened, and examine the connectors/cable for any corrosion or openings?
If you 've done all of that & your still getting bad uploads, you will likely have to go further up the support chain. Try sendin an IM to any of the red "Comcast_<username>" people on this forum, as they have contacts to escalate things.
Pretty much did that checklist. The call center folks were supposed to escalate it to an engineer but crickets so far. This same issue occurred before a few years ago and it was a config issue a kind comcast guy in the now closed direct forum fixed for me. I have a feeling this is related to some infrastructure changes made recently in my area. I'll try messaging one of the comcast folks. I looked back through older records I have of that SMC gateway config and found where it used to have three upstream channels. The third was only 16qam but it was there.
I'm happy to report that the upstream issues are fixed now and speeds are back to their norms. For everyone's information, I checked the SMC and the 3rd upstream 64qam 5120 sr channel has been re-added now. Thanks to whomever got a ticket going and fixed it this morning :-)
Very good. I suspect it was an upstream noise ingress issue, making the upstream SNR out of spec on one of the channels, and preventing it from binding.
This is why I wish customers could get access to uSNR readings; it would really help speed along the support system, and I tend to find that upstream SNR issues are pretty commonplace.
I agree completely with that. Would help many of us business customers who know what we're looking at to narrow it down before calling support. I'm just thankful for A: resolved with no truck rollout and B: being able to log into the gateway to see what I can see presently. My g.f. used to be a charter tier 2 tech, and the mantra there was always to cut down call resolution time by just doing a truck roll instead of really troublshooting it. Sad. Probably costs more to roll a truck when one does the math. I have comcast 50/50 fiber at another location besides my home office (need the qos and upstream) and it rocks.
I'm sure it absolutely does cost more for a truck visit, particularly when the original issue could have been fixed remotely/by the customer.
What ONT did Comcast give you on that 50/50 serivce? Is it the Ciena?
Yeah it was one of those. Very physically small but it has dual power supplies which I eventually plugged into different ups-es. When I did that, i received a call from comcast as it threw an alarm. Impressive. I like the monitoring.
Interesting. I have a few TP-Link fiber-to-GigE media converters that are literally pocket-size, I imagine the Comcast ONTs aren't much more complicated of a device than that.
I had to burn an extra 3750 to do the intersubnet routing but thats all. Hey do you mind sharing a part # or two of those fiber-gige boxes you're using? I need to do some stuff between floors at work. (1967 vintage building, cranky mgmt and only one liner I can use so fiber will be the pull).
Yeah, I have 2 of the TP-Link MC200CM converters. Amazon has them for ~$60 usually. They take multimode SC fiber and can run ~1800 feet. There is a 100megabit version that's roughly half the price (though I don't know why you would restrict yourself like that), and they make single-mode units that can run ~9 miles. I used them at work for an application where we needed ~1050 feet between separate buildings, and they've worked perfect.