6 Messages
Up/down speeds, corrected/uncorrected packets and more fun with a Motorola Mb7621
Earlier this year I upgraded my internet speed after years of being on a legacy plan. I've owned a Motorola Mb7621 since November of 2019 and it "just worked" and is is ostensibly mostly compatible with my new plan (1000 Mbps / 20 Mbps). But I wasn't seeing anything past 200 Mpbs / 5 Mpbs on an ethernet connection via a gigabit switch, so a tech came out, did some work at the pole, tested outside the house, tested inside, and verified that signal/noise and interference and raw bandwidth were all solid, suggesting it may be the modem. Fine, understood. I reached out to Xfinity support via Twitter at the time, and they also suggested the modem.
And the thing is, it totally could be, but what bothers me is that the 5 Mpbs upstream isn't budging. Even with pre-gigabit equipment on the heaviest of neighborhood data download days that upstream number should be way, way closer to 20 Mbps, and it's still hard-capped at 5. That makes me think it's a configuration issue but support folks seem keen to blame the customer-owned portion of the equation (shocking).
On the flip side, logging into the modem shows an amazing number of corrected and uncorrected packets (uptime about 7 days currently), of roughly 82,000 corrected and 188,000 uncorrected. That seems uncommon, so hey, maybe it really is the modem! So if anyone has any thoughts or insights about how to get closer to what I'm paying for that would be appreciated.
flatlander3
Problem Solver
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1.5K Messages
2 years ago
If you want to take a look at it yourself, I always start here: https://forums.xfinity.com/conversations/your-home-network/internet-troubleshooting-tips/602dae4ac5375f08cde52ea0
Check out your house wiring, connectors/splitters/cabling/amplifiers(if you have one). Log into your motorola and look at logs, post the signal tables, power, both up/downstream, errors. Might be your house. Might be an Xfinity infrastructure issue, but it can help in giving you a place to start. A lot of cable infrastructure has been kicking around since the 80's or longer and it all degrades over time.
(edited)
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BruceW
Gold Problem Solver
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26.3K Messages
2 years ago
Perhaps not the root of the problem, but you should be aware that the MB7621 is not approved for use with the gigabit Internet tier. See https://www.xfinity.com/support/devices and https://assets.xfinity.com/assets/dotcom/projects_2/my_device/Full-List-of-Compatible-Devices.pdf which say that the modem is good for "Wired Download Speed Up to 845 Mbps". Using devices on Internet speed tiers for which Comcast has not approved them tends to produce unexpected results, often speeds well below the tier's stated speeds and/or manufacturer's ratings.
It would be best to purchase a device approved for use with the gigabit tier, or to drop your Internet plan back to a speed for which your modem is approved.
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user_939e87
Contributor
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16 Messages
2 years ago
Would it be practical for you to rent a modem/router device for a month just to see how an Xfinity device works in your situation? I have that router and the back of my brain says Xfinity rates it up to around 600 mb./sec. Motorola's rating was higher but I don't recall what it was/is.
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flatlander3
Problem Solver
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1.5K Messages
2 years ago
Uncorrectables are not going to be the speed provisioning. Your DOCSIS 3.0 can't do the speed tier, but that's another issue. If you want to try to get that bandwidth, you will need DOCSIS 3.1 hardware that can bond enough channels. Power and SNR is good, upsteam too, but you shouldn't have the errors going on. That's noise injected from someplace. Either your place or perhaps past your house in the neighborhood.
If you can get to where it comes into your house and plug in your motorola there directly on a nice sunny day, you may find out where it is coming from really quickly. At least rule out your house wiring.
Outside of one of my locations, I found an old MOCA filter with an aluminum center conductor that was going bad/corrosion/oxidation (maybe disintegration on the inside). It was actually knocking out two upstream channels and causing errors. I just swapped it out and it worked fine. They are cheap.
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BruceW
Gold Problem Solver
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26.3K Messages
2 years ago
I don't know how accurate the Device Info page is generally, but I can tell you that the one I see is wildly inaccurate when it comes to "your plan speed", and always has been. It says my MB7621 is "compatible with your service download speed of 10 Mbps", but I have NEVER had internet service at that speed. OTOH the values listed on https://www.xfinity.com/learn/internet-service/auth are correct. "Your mileage may vary."
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flatlander3
Problem Solver
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1.5K Messages
2 years ago
Might depend on your market a lot too on what is "supported" at what "speed", plus the infrastructure around you. We all might be getting different answers on supported or not. I also suspect at some point, perhaps not for a while still, they'll discontinue all of the DOCSIS 3.0.
A while ago, a big storm wiped out a bunch of stuff at one of my locations. After they fixed it, that one is pretty snappy using identical hardware compared to another cable location. The replaced lines still have some errors reported from time to time when there's a lot of wind and weather (overhead lines in a lot of places), but the error counts level out with the weather and errors don't increase then. I don't know if that is what is going on at your location or not.
It's a similar direct pole run that you have at that location, but no splitter involved. It may also help to take the connectors apart and shine up that center copper a bit on them. Usually does nothing, but it can't hurt. Bypass the splitter if you can for a test. Even check grounding if you got a good multi-meter around. It's supposed to be grounded somewhere, to something (codes vary by even by city).
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