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How to communicate Comcast upstream issue to Support?

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How to communicate Comcast upstream issue to Support?

I'm in the unfortunately situation where I'm seeing packet loss when going upstream from my modem with no indicators about anything being wrong on my local network.  Going out from my local router to Comcast I see sporadic drops of upstream traffic at rates of anywhere from 3% to 10% over a 120s period.  One hour averages approximately 6% packet loss on an ICMP ping to google for example.


I'd previously had this issue and replaced my modem with a new Arris DOCSIS 3.1 and even ran new RG6 cable from my box to my network closet.  When I previously had this issue I could see a good amount of Correctable and Uncorrectable errors on my modem status page, but now everything looks pristine in terms of errors and signal (as best I can tell).


Example ping summary ran from my router (ie, direct connection to modem):


--- ping statistics ---
99 packets transmitted, 92 packets received, 7% packet loss
round-trip min/avg/max = 15.335/17.684/74.069 ms


I attempted to contact support once, got sent through the 'restart your modem' spiel multiple times and was even asked to use the "Activate" link, as if they thought my MAC wasn't registered.  I believe this comes down to the front-line support folks having issues understanding sporadic packet loss as being separate from complete loss of service.


I'm at a loss how to proceed since the only option I've been offered was to have a service technician come out, but with no errors showing on my modem, I'm having a hard time imagining this is a line issue (especially after redoing and line testing all the cable runs myself). 


Any suggestions on how I could proceed with engaging Comcast?


(Edit to clarify: All client access is wired over internal Cat6 runs to a core switch, using a router running NAT/uPNP mode with a 1-WAN/1-LAN.  WiFi access stations are in bridge mode, segmented into a guest network via VLAN.  All testing above was conducted over ethernet cabling.)


Modem Status (2h uptime, including above demo ping run with 7% packet loss):


Acquire Downstream Channel585000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
Configuration FileOK 
DOCSIS Network Access EnabledAllowed 

Downstream Bonded Channels
Channel IDLock StatusModulationFrequencyPowerSNR/MERCorrectedUncorrectables
21LockedQAM256585000000 Hz-6.0 dBmV40.2 dB00
1LockedQAM256459000000 Hz-4.0 dBmV41.3 dB00
2LockedQAM256465000000 Hz-4.1 dBmV41.2 dB00
3LockedQAM256471000000 Hz-4.0 dBmV41.1 dB00
4LockedQAM256477000000 Hz-4.0 dBmV41.2 dB00
5LockedQAM256483000000 Hz-4.1 dBmV41.1 dB00
6LockedQAM256489000000 Hz-4.5 dBmV40.9 dB00
7LockedQAM256495000000 Hz-4.6 dBmV40.8 dB00
8LockedQAM256507000000 Hz-4.7 dBmV40.9 dB00
9LockedQAM256513000000 Hz-4.8 dBmV40.8 dB00
10LockedQAM256519000000 Hz-5.1 dBmV39.9 dB00
11LockedQAM256525000000 Hz-5.1 dBmV40.7 dB00
12LockedQAM256531000000 Hz-5.3 dBmV40.6 dB00
13LockedQAM256537000000 Hz-5.4 dBmV40.4 dB00
14LockedQAM256543000000 Hz-5.7 dBmV40.5 dB00
15LockedQAM256549000000 Hz-5.7 dBmV40.6 dB00
16LockedQAM256555000000 Hz-5.7 dBmV40.5 dB00
17LockedQAM256561000000 Hz-5.8 dBmV40.5 dB00
18LockedQAM256567000000 Hz-6.1 dBmV40.4 dB00
19LockedQAM256573000000 Hz-6.2 dBmV40.5 dB00
20LockedQAM256579000000 Hz-6.1 dBmV40.4 dB00
22LockedQAM256591000000 Hz-6.4 dBmV40.2 dB00
23LockedQAM256597000000 Hz-6.5 dBmV40.3 dB00
24LockedQAM256603000000 Hz-6.5 dBmV40.3 dB00
25LockedQAM256609000000 Hz-6.5 dBmV40.2 dB00
26LockedQAM256615000000 Hz-7.0 dBmV39.9 dB00
27LockedQAM256621000000 Hz-7.4 dBmV39.6 dB00
28LockedQAM256627000000 Hz-7.3 dBmV39.2 dB00
29LockedQAM256633000000 Hz-7.0 dBmV39.4 dB00
30LockedQAM256639000000 Hz-7.3 dBmV39.3 dB00
31LockedQAM256645000000 Hz-7.7 dBmV39.0 dB00
32LockedQAM256651000000 Hz-7.8 dBmV38.9 dB00
159LockedOther690000000 Hz-7.6 dBmV36.0 dB5369253330

Upstream Bonded Channels
ChannelChannel IDLock StatusUS Channel TypeFrequencyWidthPower
13LockedSC-QAM Upstream29200000 Hz6400000 Hz37.0 dBmV
21LockedSC-QAM Upstream16200000 Hz6400000 Hz36.0 dBmV
32LockedSC-QAM Upstream22700000 Hz6400000 Hz36.0 dBmV
44LockedSC-QAM Upstream35700000 Hz6400000 Hz38.0 dBmV
55LockedSC-QAM Upstream41200000 Hz1600000 Hz40.0 dBmV