Upstream channel power levels too low - what to do.

I'm paying for the most expensive plan available at my apartment complex (Gigabit). I'm getting ~600 Mbps download (which I'm okay with), and ~5 Mbps upload. The upload speed has become unbearable and, honestly, unacceptable for a top-tier modern internet plan.

For reference, 5 Mbps upload speeds means it takes 40 minutes to upload a 10-minute home video to social media. 5 Mbps means streaming gameplay on something like Twitch is guaranteed to be horrible quality. 5 Mbps means having choppy video calls with family back home. 5 Mbps means my personal file server is painfully slow outside of the local network.

When I called support this morning, after 40 minutes of running identical speed tests and four separate modem restarts, the support agent directed me to call my modem manufacturer Arris. Instead of doing that, I looked into my modem (SB6190) myself and found this:

Upstream Bonded Channels
Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	3	5120 kSym/s	23.70 MHz	43.25 dBmV
2	Locked	ATDMA	2	5120 kSym/s	30.10 MHz	43.25 dBmV
3	Locked	ATDMA	1	5120 kSym/s	36.50 MHz	43.25 dBmV

Arris' FAQ says that acceptable upstream signal levels should be no less than 45 dBmV:

https://arris.secure.force.com/consumers/articles/General_FAQs/SB6190-Cable-Signal-Levels/

My modem is reading a power level of 43.25. In this situation the FAQ directs me to ask my service provider to adjust the levels. So here I am, asking. Please, sir, may I have some more upstream bandwidth?

@ComcastMorgan this is extremely similar to another thread you answered: https://forums.xfinity.com/t5/Your-Home-Network/upstream-channel-power-levels-too-low-what-to-do/td-p/3195031

The solution there appears to have been a modem swap, but the symptoms were different (outages and packet loss vs. upstream bandwidth). Do you believe a modem swap would help me here as well?

This conversation is no longer open for comments or replies and is no longer visible to community members.

Responses

Accepted Solution

EG

Expert

•

103.5K Messages

5 years ago

The upstream power is fine. The SB6190 is only a DOCSIS 3.0 capable modem. You will never get gig speeds with it. You need to use a DOCSIS 3.1 capable modem such as one of these;

https://www.amazon.com/Next-Generation-ARRIS-SURFboard-SB8200-DOCSIS/dp/B01N6SKK1G

https://www.amazon.com/Motorola-MB8600-Certified-Comcast-Communications/dp/B0723599RQ

https://www.amazon.com/NETGEAR-CM1000-DOCSIS-Ultra-High-download/dp/B01I5TJGSE

shoffing1

New Poster

•

4 Messages

5 years ago

DOCSIS 3.0 is capable of up to 200 Mbit/s. I'm getting five. Are you SURE a new modem is the solution?

DOCSIS version^[14]	Production date	Maximum downstream capacity	Maximum upstream capacity	Features
1.0	1997	40 Mbit/s	10 Mbit/s	Initial release
1.1	2001	40 Mbit/s	10 Mbit/s	Added VOIP capabilities, standardized the DOCSIS 1.0 QoS mechanisms
2.0	2002	40 Mbit/s	30 Mbit/s	Enhanced upstream data rates
3.0	2006	1.2 Gbit/s	200 Mbit/s	Significantly increased downstream/upstream data rates, introduced support for IPv6, introduced channel bonding
3.1	2013	10 Gbit/s	1–2 Gbit/s	Significantly increased downstream/upstream data rates, restructured channel specifications
4.0	2017	10 Gbit/s	10 Gbit/s	Introduces support for fully symmetrical speeds

EG

Expert

•

103.5K Messages

5 years ago

They will not push a gigabit speed tier configuration file to a DOCSIS 3.0 modem. It will default to using a slower speed tier config.

EG

Expert

•

103.5K Messages

5 years ago

@shoffing1 wrote:

I don't know if I believe you about the active speed tier degredation, though.

Believe what you will.....

shoffing1

New Poster

•

4 Messages

5 years ago

Okay, I'll get a new modem with 3.1 now.

I don't know if I believe you about the active speed tier degredation, though. There are no speed tiers between 300 Mbps and 1000 Mbps, and I've been getting ~600:

Download Speed Tier	Measured Speed (Peak)	Upload Speed Tier	Measured Speed (Peak)
5 Mbps	5.95 Mbps⁽¹⁾	1 Mbps	1.21 Mbps⁽¹⁾
10 Mbps	11.8 Mbps⁽¹⁾	1 Mbps	1.21 Mbps⁽¹⁾
10 Mbps	11.8 Mbps⁽¹⁾	2 Mbps	2.4 Mbps⁽¹⁾
25 Mbps	29.41 Mbps	0.768 Mbps	0.89 Mbps⁽¹⁾
50 Mbps	57.56 Mbps⁽¹⁾	5 Mbps	5.92 Mbps
75 Mbps	83.11 Mbps	10 Mbps	11.89 Mbps
100 Mbps	111.07 Mbps	5 Mbps	5.92 Mbps
150 Mbps	151.65 Mbps⁽¹⁾	20 Mbps	23.73 Mbps⁽¹⁾
200 Mbps	221.07 Mbps⁽¹⁾	10 Mbps	11.89 Mbps⁽¹⁾
250 Mbps	265.1 Mbps⁽¹⁾	25 Mbps	29.7 Mbps⁽¹⁾
300 Mbps	318.2 Mbps⁽¹⁾	25 Mbps	29.7 Mbps⁽¹⁾
1 Gbps⁽²⁾	931.51 Mbps⁽¹⁾⁽³⁾	35 Mbps⁽²⁾	38.25 Mbps⁽¹⁾
2 Gbps	2,086 Mbps⁽¹⁾	2 Gbps	2,060 Mbps⁽¹⁾
⁽¹⁾Based on independent measurements by Comcast		⁽²⁾Available in most, but not all, markets
⁽³⁾Due to current technological limitations related to the capabilities of Ethernet ports in current hardware, download speeds through those ports for 1 Gbps service are limited as specified in the table above.

I suppose they could be putting me on an unlisted "tier". At the very least a new modem will improve my download speeds, I see that now. But my biggest concern remains the upload speed. I'm cautiously hopeful those will improve too.

EG

Expert

•

103.5K Messages

5 years ago

How 'bout that ! Happy surfing !!

shoffing1

New Poster

•

4 Messages

5 years ago

You were right, my modem was the issue. I went to Microcenter and picked up a DOCSIS 3.1 modem (the motorola one you sent).

The support person should have seen this incompatability, and I resent the fact that I spent 40 minutes on the phone accomplishing nothing this morning, but I'm glad to have the problem resolved. I'll be sure to come to the forums first in the future.

I'm getting 40 Mbps up right now, which is better than what Comcast "advertises" in that table above.

Thank you for your help! I really appreciate it.

Your Home Network

shoffing1

Upstream channel power levels too low - what to do.

EG

shoffing1

EG

EG

shoffing1

EG

shoffing1

New to the Community?