Regular Visitor
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4 Messages
Downstream slow MB7621 modem
Hi,
Over the last week or so I've been having trouble streaming video. Today I ran a speed test hardwired to my MB7621 to confirm speed is much less than my speed tier. Approximately 250Mbps vs. the 1Gbps tier I'm subscribed to. I've included the log info below. Does anyone see any issues I can use to further my troubleshooting efforts (I've already rebooted several times). Thanks.
| Cable Specification Version | DOCSIS 3.0 |
| Hardware Version | V1.0 |
| Software Version | 7621-5.7.1.10 |
| Cable Modem MAC Address | |
| Cable Modem Serial Number | |
| CM Certificate | Installed |
| 5.7.1mp4 |
| Startup Step | Status | Comment |
| Acquire Downstream Channel | 531000000 Hz | Locked |
| Upstream Connection | OK | Operational |
| Boot State | OK | Operational |
| Configuration File | OK | |
| Security | Enabled | BPI+ |
| System Up Time | 0 days 05h:35m:47s |
| Network Access | Allowed |
| Channel | Lock Status | Modulation | Channel ID | Freq. (MHz) | Pwr (dBmV) | SNR (dB) | Corrected | Uncorrected |
| 1 | Locked | QAM256 | 9 | 531.0 | -1.8 | 39.0 | 0 | 0 |
| 2 | Locked | QAM256 | 42 | 405.0 | -2.6 | 38.9 | 0 | 0 |
| 3 | Locked | QAM256 | 43 | 411.0 | -2.7 | 38.8 | 0 | 0 |
| 4 | Locked | QAM256 | 44 | 417.0 | -2.7 | 38.9 | 0 | 0 |
| 5 | Locked | QAM256 | 45 | 423.0 | -2.6 | 38.9 | 0 | 0 |
| 6 | Locked | QAM256 | 38 | 435.0 | -2.2 | 39.0 | 0 | 0 |
| 7 | Locked | QAM256 | 39 | 441.0 | -2.0 | 39.0 | 0 | 0 |
| 8 | Locked | QAM256 | 40 | 447.0 | -1.9 | 38.9 | 0 | 0 |
| 9 | Locked | QAM256 | 41 | 453.0 | -2.0 | 38.9 | 0 | 0 |
| 10 | Locked | QAM256 | 32 | 459.0 | -2.1 | 38.9 | 0 | 0 |
| 11 | Locked | QAM256 | 34 | 465.0 | -2.0 | 38.9 | 0 | 0 |
| 12 | Locked | QAM256 | 35 | 471.0 | -1.9 | 38.5 | 0 | 0 |
| 13 | Locked | QAM256 | 36 | 477.0 | -2.0 | 38.9 | 0 | 0 |
| 14 | Locked | QAM256 | 1 | 483.0 | -2.0 | 38.9 | 0 | 0 |
| 15 | Locked | QAM256 | 2 | 489.0 | -1.8 | 38.9 | 0 | 0 |
| 16 | Locked | QAM256 | 3 | 495.0 | -1.9 | 38.9 | 0 | 0 |
| 17 | Locked | QAM256 | 4 | 501.0 | -2.6 | 39.4 | 0 | 0 |
| 18 | Locked | QAM256 | 5 | 507.0 | -2.5 | 39.4 | 0 | 0 |
| 19 | Locked | QAM256 | 6 | 513.0 | -2.3 | 39.5 | 0 | 0 |
| 20 | Locked | QAM256 | 7 | 519.0 | -2.4 | 39.3 | 0 | 0 |
| 21 | Locked | QAM256 | 8 | 525.0 | -2.5 | 39.4 | 0 | 0 |
| 22 | Locked | QAM256 | 10 | 537.0 | -2.1 | 37.6 | 0 | 0 |
| 23 | Locked | QAM256 | 11 | 543.0 | -2.6 | 39.3 | 0 | 0 |
| 24 | Locked | QAM256 | 12 | 549.0 | -2.9 | 39.2 | 0 | 0 |
| Total | 0 | 0 |
| Channel | Lock Status | Channel Type | Channel ID | Symb. Rate (Ksym/sec) | Freq. (MHz) | Pwr (dBmV) |
| 1 | Locked | ATDMA | 2 | 5120 | 29.2 | 48.5 |
| 2 | Locked | ATDMA | 1 | 5120 | 35.6 | 49.0 |
| 3 | Locked | ATDMA | 3 | 5120 | 22.8 | 47.3 |
| 4 | Locked | ATDMA | 4 | 5120 | 16.4 | 46.3 |
| 5 | Locked | ATDMA | 5 | 2560 | 40.4 | 48.8 |
| 6 | Not Locked | Unknown | 0 | 0 | 0 | 0.0 |
| 7 | Not Locked | Unknown | 0 | 0 | 0 | 0.0 |
| 8 | Not Locked | Unknown | 0 | 0 | 0 | 0.0 |
XfinityGabby
Official Employee
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1.5K Messages
2 months ago
Hello, @DT_UM. Thanks for reaching our team on Forums regarding your speed concerns. I appreciate you attempting to reboot your device in hopes of getting your speeds to where it should be. Can you please make sure that the coax cable is finger tight on both the modem and wall plate, also can you confirm if there's a splitter connected to the modem?
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EG
Expert
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107.1K Messages
2 months ago
@DT_UM
First. You'll never be able to get your subscribed to speeds with that modem. Comcast rates it to 845 Mbps;
https://www.xfinity.com/support/devices#details
Second. This may or may not be the root cause of the problem (YMMV) but it should be addressed regardless. First.
The upstream power is on the high side and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.
In an effort to try to obtain better connectivity / more wiggle room, check to see if there are any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, etc. Splitters should be swapped with known to be good / new ones to test.
Also check the coax cable for any damage such as cuts, nicks, abrasions, kinks, sharp bends, etc.
If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two-way splitter connected directly off of the drop from the street / pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.
Good luck with it !
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