Community Forum

Speed Loss with Gigabit subscription

staceytheking
Regular Visitor

Speed Loss with Gigabit subscription

I upgraded to 1gbps speed back in March and updated my cable modem to take advantage of the new plan (new modem is an Arris t25). Ever since then, I get blazing fast speed when the modem first connects (~900mbps), but the speed drops down to ~30mbps after a random period of time. I have been on multiple chats with Xfinity support and the issue keeps occurring. Reboot the modem-->very fast connection-->eventual degradation of speed-->30mbps until I reboot the modem. 

I called Arris support and they told me that the Upstream QAM power was outside of the acceptible range (data posted below) and that this is an Xfinity issue. When I asked about this with Xfinity support, they said that the line looks fine and that it must be an issue with the internal wiring. The cable comes to my house via a buried line that goes from the street to the house, so I hooked up my modem directly to that line (bypassing all internal wiring) and the Upstream QAM power levels did not change (in fact they got lower, which is weird but I'm not an engineer so [insert shrug emoji]). At that point, support said they would re-provision my service and that should fix it. It did not.

This is VERY frustrating. I'm happy to re-wire my house to resolve the issue since Xfinity techs aren't allowed to enter homes, but I'm not convinced that's the answer. Any assistance from these threads would be greatly appreciated.

RF Parameters

Downstream QAM

  DCID Freq Power SNR Modulation Octets Correcteds Uncorrectables
Downstream 1 1 453.00 MHz -1.00 dBmV 40.95 dB 256QAM 155451193 0 0
Downstream 2 2 459.00 MHz -1.30 dBmV 40.37 dB 256QAM 33104877 0 0
Downstream 3 3 465.00 MHz -1.10 dBmV 40.95 dB 256QAM 33242645 0 0
Downstream 4 4 471.00 MHz -0.80 dBmV 40.37 dB 256QAM 33257091 0 0
Downstream 5 5 477.00 MHz -0.50 dBmV 40.95 dB 256QAM 30249213 0 0
Downstream 6 6 483.00 MHz -0.70 dBmV 40.95 dB 256QAM 32565109 11 0
Downstream 7 7 489.00 MHz -0.20 dBmV 40.37 dB 256QAM 32402550 0 0
Downstream 8 8 495.00 MHz -0.10 dBmV 40.37 dB 256QAM 32445804 0 0
Downstream 9 9 507.00 MHz 0.10 dBmV 40.37 dB 256QAM 31056753 10 0
Downstream 10 10 513.00 MHz 0.20 dBmV 40.37 dB 256QAM 33287852 7 0
Downstream 11 11 519.00 MHz 0.00 dBmV 40.37 dB 256QAM 33301379 0 0
Downstream 12 12 525.00 MHz -0.40 dBmV 40.37 dB 256QAM 33376668 0 0
Downstream 13 13 531.00 MHz -0.30 dBmV 40.95 dB 256QAM 30953960 0 0
Downstream 14 14 537.00 MHz -0.10 dBmV 40.37 dB 256QAM 33253055 0 0
Downstream 15 15 543.00 MHz -0.30 dBmV 40.95 dB 256QAM 33290730 0 0
Downstream 16 16 549.00 MHz -0.70 dBmV 40.95 dB 256QAM 33367718 0 0
Downstream 17 17 555.00 MHz -0.30 dBmV 40.95 dB 256QAM 31005923 0 0
Downstream 18 18 561.00 MHz 0.00 dBmV 40.37 dB 256QAM 33411325 0 0
Downstream 19 19 567.00 MHz -0.30 dBmV 40.37 dB 256QAM 33331893 0 0
Downstream 20 20 573.00 MHz -0.40 dBmV 40.37 dB 256QAM 33211846 0 0
Downstream 21 21 579.00 MHz 0.20 dBmV 40.95 dB 256QAM 30977485 0 0
Downstream 22 22 585.00 MHz -0.20 dBmV 40.37 dB 256QAM 33330472 0 0
Downstream 23 23 591.00 MHz -0.40 dBmV 40.37 dB 256QAM 33433711 0 0
Downstream 24 24 597.00 MHz -0.30 dBmV 40.37 dB 256QAM 33267164 0 0
Downstream 25 25 603.00 MHz -0.30 dBmV 40.95 dB 256QAM 32868246 0 0
Downstream 26 26 609.00 MHz -0.30 dBmV 40.37 dB 256QAM 35508942 0 0
Downstream 27 27 615.00 MHz -0.30 dBmV 40.95 dB 256QAM 35539254 0 0
Downstream 28 28 621.00 MHz -0.40 dBmV 40.37 dB 256QAM 35531400 0 0
Downstream 29 29 627.00 MHz 0.20 dBmV 40.95 dB 256QAM 32869722 0 0
Downstream 30 30 633.00 MHz 0.00 dBmV 40.37 dB 256QAM 35560321 0 0
Downstream 31 31 639.00 MHz -0.50 dBmV 40.37 dB 256QAM 35450554 0 0
Downstream 32 32 645.00 MHz -0.20 dBmV 40.37 dB 256QAM 35548701 0 0
Reset FEC Counters

Downstream OFDM

  FFT Type Channel Width(MHz) # of Active Subcarriers First Active Subcarrier(MHz) Last Active Subcarrier(MHz) Average RxMER(dB)
Pilot PLC Data
Downstream 2 4K 50 1004 697 748 49 42 43
 

Upstream QAM

  UCID Freq Power Channel Type Symbol Rate Modulation
Upstream 1 3 23.70 MHz 38.25 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM
Upstream 2 4 17.30 MHz 38.25 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM
Upstream 3 2 30.10 MHz 38.75 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM
Upstream 4 1 36.50 MHz 38.75 dBmV DOCSIS2.0 (ATDMA) 5120 kSym/s 64QAM