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Thread: Comcast issues in Northern Colorado... or is it my modem

  1. #1

    Comcast issues in Northern Colorado... or is it my modem

    For nearly 48 hours my internet has been terrible. It has been slow, web pages have timed out, I've had different pages take 5 minutes or longer to load, some of them partially loading the page, then claiming to be done when only the background and maybe a header have come up. To make matters worse, when I do finally manage to get a speed test page loaded, all the tests report my download speeds are EXCELLENT, but it never seems to be able to finish or get to the upload speeds...

    After attempting everything I could think of, including kicking every computer off my wireless network, power cycling EVERYTHING a few times and making sure there were no other problems, I called Comcast.
    She told me from their end, there are no problems. I did a bunch of stuff to appease her including unhooking my router, plugging my modem directly into my computer, and those sorts of things. Nothing really worked, and she told me it must be my modem, router (even though that was completely shut off), or one of the cables... either from the wall to my modem or from my modem to my computer.

    I know it's not my router. The apartment complex I live in provides broadband internet from some company called Pavlov. It's terrible, so my roommates and I decided to get Comcast. With the internet as it was, I hooked my router up to the Pavlov internet only to discover that it worked just fine, so router is out of the question.
    I've swapped out a number of the cables, and nothing seems to be changing.
    This modem, a Motorola Surfboard 5120, is only a few months old so I highly doubt it is defunct, not to mention when I go to 192.168.100.1 it loads in a flash. On the status page, everything says "done" and modem status is "operational"

    My signal page says the following:
    Downstream Value
    Frequency 525000000 Hz
    Signal to Noise Ratio 36 dB
    QAM QAM256
    Network Access Control Object ON
    Power Level 3 dBmV
    The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading
    Upstream Value
    Channel ID 9
    Frequency 21000000 Hz
    Ranging Service ID 7546
    Symbol Rate 2.560 Msym/s
    Power Level 42 dBmV


    Have spoken with Comcast for many hours to at least 5 different individuals. Here's what I know for sure (some reiteration) based on talking with them and my own knowledge:

    1. It's not my firewall or my cache (thank you Comcast, for making me do that...)
    2. Pinging comcast.com has no problem, and they can ping me with fast speeds.
    3. Tracert shows no issues, to any website.
    4. My modem appears to be working properly as it shows up when i look for it, it responds to ping, etc.
    5. I've removed the router from the equation, so it's not that.
    6. When I run a speed test, any speed test, if it actually loads, it says i have blazingly fast download speeds, but it hangs on the upload portion
    7. the problem exists consistently on a Vista machine and two different XP machines, as well as connecting with a wire to an Xbox 360
    8. Web pages take FOREVER to load, many time out or claim the server is not responding

    The point is, I'm totally at a loss. Most web pages take FOREVER to load. Every time my roommate logs into WoW he doesn't even get connected, and then it tells him he has lost connection to the server. Comcast claims everything on their end is great.

    They are still convinced my modem is broken. They are sending a technician out on Monday, but i'd prefer not to be charged. If anyone has an idea, advice, a suggestion, anything, please let me know.

    Thank you for any help, advice or whatever you can provide.

  2. #2
    Elite Member trogers's Avatar
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    Sounds like the problem is a choked up upload bandwidth.

    Try this test. Click the 'Statistics' button and post the pop-up report:

    http://miranda.ctd.anl.gov:7123/

  3. #3
    Connected to: nitro.ucsc.edu -- Using IPv4 address
    Another client is currently being served, your test will begin within 45 seconds
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 1.0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 5.94Mb/s
    Your PC is connected to a Cable/DSL modem
    Information: Other network traffic is congesting the link
    [C2S]: Packet queuing detected

  4. #4
    I ran the test twice

    First time:

    Connected to: nitro.ucsc.edu -- Using IPv4 address
    Another client is currently being served, your test will begin within 45 seconds
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 1.0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 5.94Mb/s
    Your PC is connected to a Cable/DSL modem
    Information: Other network traffic is congesting the link
    [C2S]: Packet queuing detected


    Second Time (plus statistics, forgot the first time):
    WEB100 Enabled Statistics:
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 3.0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 11.65Mb/s

    ------ Client System Details ------
    OS data: Name = Windows Vista, Architecture = x86, Version = 6.0
    Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0

    ------ Web100 Detailed Analysis ------
    Cable modem/DSL/T1 link found.
    Link set to Full Duplex mode
    Information: throughput is limited by other network traffic.
    Good network cable(s) found
    Normal duplex operation found.

    Web100 reports the Round trip time = 66.41 msec; the Packet size = 1260 Bytes; and
    No packet loss was observed.
    S2C throughput test: Packet queuing detected: 1.13%
    This connection is receiver limited 90.78% of the time.
    This connection is network limited 9.07% of the time.

    Web100 reports TCP negotiated the optional Performance Settings to:
    RFC 2018 Selective Acknowledgment: ON
    RFC 896 Nagle Algorithm: ON
    RFC 3168 Explicit Congestion Notification: OFF
    RFC 1323 Time Stamping: OFF
    RFC 1323 Window Scaling: ON

    Server 'nitro.ucsc.edu' is not behind a firewall. [Connection to the ephemeral port was successful]
    Client is not behind a firewall. [Connection to the ephemeral port was successful]
    Information: Network Middlebox is modifying MSS variable
    Server IP addresses are preserved End-to-End
    Client IP addresses are preserved End-to-End

  5. #5
    Elite Member trogers's Avatar
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    Quote Originally Posted by scudmuffin View Post
    I ran the test twice

    First time:

    Connected to: nitro.ucsc.edu -- Using IPv4 address
    Another client is currently being served, your test will begin within 45 seconds
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 1.0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 5.94Mb/s
    Your PC is connected to a Cable/DSL modem
    Information: Other network traffic is congesting the link
    [C2S]: Packet queuing detected


    Second Time (plus statistics, forgot the first time):
    WEB100 Enabled Statistics:
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 3.0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 11.65Mb/s

    ------ Client System Details ------
    OS data: Name = Windows Vista, Architecture = x86, Version = 6.0
    Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0

    ------ Web100 Detailed Analysis ------
    Cable modem/DSL/T1 link found.
    Link set to Full Duplex mode
    Information: throughput is limited by other network traffic.
    Good network cable(s) found
    Normal duplex operation found.

    Web100 reports the Round trip time = 66.41 msec; the Packet size = 1260 Bytes; and
    No packet loss was observed.
    S2C throughput test: Packet queuing detected: 1.13%
    This connection is receiver limited 90.78% of the time.
    This connection is network limited 9.07% of the time.

    Web100 reports TCP negotiated the optional Performance Settings to:
    RFC 2018 Selective Acknowledgment: ON
    RFC 896 Nagle Algorithm: ON
    RFC 3168 Explicit Congestion Notification: OFF
    RFC 1323 Time Stamping: OFF
    RFC 1323 Window Scaling: ON

    Server 'nitro.ucsc.edu' is not behind a firewall. [Connection to the ephemeral port was successful]
    Client is not behind a firewall. [Connection to the ephemeral port was successful]
    Information: Network Middlebox is modifying MSS variable
    Server IP addresses are preserved End-to-End
    Client IP addresses are preserved End-to-End
    Your MTU is set too low at 1300. ComCast uses MTU set to 1500.

    Try the following with TCP Optimizer to increase your MTU:

    General Settings tab:
    Custom settings - check
    Modify All Network Adapters - check
    network adapter selection - your NIC
    MTU 1500
    TTL - 64
    TCP Receive Window - leave blank
    MTU Discovery - Yes
    Black Hole Detect - No
    Selective Acks - Yes
    Max Duplicate ACKs - 2
    TCP 1323 Options:
    Windows Scaling - uncheck
    Timestamps - uncheck

    Advanced Settings tab:
    Max Connections per Server - 10
    Max Connections per 1.0 Server - 20
    LocalPriority - 1
    Host Priority - 1
    DNSPriority - 1
    NetbtPriority - 1
    Lan Browsing speedup - optimized
    QoS: NonBestEffortLimit - 0
    ToS: DisableUserTOSSetting - 0
    ToS: DefaultTOSValue - 80
    MaxNegativeCacheTtl - 0
    NetFailureCacheTime - 0
    NegativeSOACache Time - 0
    LAN Request Buffer Size - 32768
    Then select "Apply Changes" and reboot to take effect

    After reboot, post a new TCP Analyzer report to see if your MTU increases, and do the miranda test again.

  6. #6
    Ohh Hell yeah.. Sava700's Avatar
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    comcast is rolling out upload power boost so keep in mind that when they are updating area's you might see issues from time to time and to make matters worse the tech support you call have no idea what is going on from the Eng side of everything. Hell I had a few tell me they didn't even know what powerboost was and it was clearly explained on their own website .. do a speed test and post the result please

    www.speedtest.net

  7. #7
    Well this is starting to seem pretty strange.
    Ran two tests with these results:

    Test 1:

    WEB100 Enabled Statistics:
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 11.62Mb/s

    ------ Client System Details ------
    OS data: Name = Windows Vista, Architecture = x86, Version = 6.0
    Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0

    ------ Web100 Detailed Analysis ------
    Interprocess communications failed, unknown link type.
    Link set to Full Duplex mode
    Information: throughput is limited by other network traffic.
    Good network cable(s) found
    Normal duplex operation found.

    Web100 reports the Round trip time = 75.15 msec; the Packet size = 1260 Bytes; and
    No packet loss was observed.
    C2S throughput test: Packet queuing detected: 100.0%
    S2C throughput test: Packet queuing detected: 1.00%
    This connection is receiver limited 88.42% of the time.
    This connection is network limited 11.48% of the time.

    Web100 reports TCP negotiated the optional Performance Settings to:
    RFC 2018 Selective Acknowledgment: ON
    RFC 896 Nagle Algorithm: ON
    RFC 3168 Explicit Congestion Notification: OFF
    RFC 1323 Time Stamping: OFF
    RFC 1323 Window Scaling: ON

    Server 'nitro.ucsc.edu' is not behind a firewall. [Connection to the ephemeral port was successful]
    Client is not behind a firewall. [Connection to the ephemeral port was successful]
    Information: Network Middlebox is modifying MSS variable
    Server IP addresses are preserved End-to-End
    Client IP addresses are preserved End-to-End




    Test 2:

    WEB100 Enabled Statistics:
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 11.60Mb/s

    ------ Client System Details ------
    OS data: Name = Windows Vista, Architecture = x86, Version = 6.0
    Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0

    ------ Web100 Detailed Analysis ------
    Interprocess communications failed, unknown link type.
    Link set to Full Duplex mode
    Information: throughput is limited by other network traffic.
    Good network cable(s) found
    Normal duplex operation found.

    Web100 reports the Round trip time = 77.24 msec; the Packet size = 1260 Bytes; and
    No packet loss was observed.
    C2S throughput test: Packet queuing detected: 100.0%
    S2C throughput test: Packet queuing detected: 1.05%
    This connection is receiver limited 87.77% of the time.
    This connection is network limited 12.12% of the time.

    Web100 reports TCP negotiated the optional Performance Settings to:
    RFC 2018 Selective Acknowledgment: ON
    RFC 896 Nagle Algorithm: ON
    RFC 3168 Explicit Congestion Notification: OFF
    RFC 1323 Time Stamping: OFF
    RFC 1323 Window Scaling: ON

    Server 'nitro.ucsc.edu' is not behind a firewall. [Connection to the ephemeral port was successful]
    Client is not behind a firewall. [Connection to the ephemeral port was successful]
    Information: Network Middlebox is modifying MSS variable
    Server IP addresses are preserved End-to-End
    Client IP addresses are preserved End-to-End



    That being said, I ran 3 speed tests at speedtest.net. Well, I ran 7, but, well... here's what happened:
    1. Had to try to load the page 4 times, finally loaded, test claimed to start but never gave back a ping, test never started. Waited 5 minutes.

    2. Page loaded up pretty quick, download speed went through (forgot the speed) but upload never went through.

    3. Page loaded. Download results came back really fast of 18680 kb/s. Upload results took 3 minutes but came back as 508 kb/s

    4. Had to reload the page 5 times, ran it, nothing came back.

    5. Page loaded kind of slowly, download speed came back 16112 kb/s, upload speed took 4 minutes to show up and came back as 720 kb/s

    6. Same as 4

    7. Page loaded really fast, test ran, download of 10546 kb/s. Upload speed never came back and the page says it's done.


    I haven't made any other changes at this point. Results are same/similar on my roommates computer. These connections are from the wall to the modem to the PC.

  8. #8
    Elite Member trogers's Avatar
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    Quote Originally Posted by scudmuffin View Post
    Well this is starting to seem pretty strange.
    Ran two tests with these results:

    Test 1:

    WEB100 Enabled Statistics:
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 11.62Mb/s

    ------ Client System Details ------
    OS data: Name = Windows Vista, Architecture = x86, Version = 6.0
    Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0

    ------ Web100 Detailed Analysis ------
    Interprocess communications failed, unknown link type.
    Link set to Full Duplex mode
    Information: throughput is limited by other network traffic.
    Good network cable(s) found
    Normal duplex operation found.

    Web100 reports the Round trip time = 75.15 msec; the Packet size = 1260 Bytes; and
    No packet loss was observed.
    C2S throughput test: Packet queuing detected: 100.0%
    S2C throughput test: Packet queuing detected: 1.00%
    This connection is receiver limited 88.42% of the time.
    This connection is network limited 11.48% of the time.

    Web100 reports TCP negotiated the optional Performance Settings to:
    RFC 2018 Selective Acknowledgment: ON
    RFC 896 Nagle Algorithm: ON
    RFC 3168 Explicit Congestion Notification: OFF
    RFC 1323 Time Stamping: OFF
    RFC 1323 Window Scaling: ON

    Server 'nitro.ucsc.edu' is not behind a firewall. [Connection to the ephemeral port was successful]
    Client is not behind a firewall. [Connection to the ephemeral port was successful]
    Information: Network Middlebox is modifying MSS variable
    Server IP addresses are preserved End-to-End
    Client IP addresses are preserved End-to-End




    Test 2:

    WEB100 Enabled Statistics:
    Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done
    checking for firewalls . . . . . . . . . . . . . . . . . . . Done
    running 10s outbound test (client-to-server [C2S]) . . . . . 0kb/s
    running 10s inbound test (server-to-client [S2C]) . . . . . . 11.60Mb/s

    ------ Client System Details ------
    OS data: Name = Windows Vista, Architecture = x86, Version = 6.0
    Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0

    ------ Web100 Detailed Analysis ------
    Interprocess communications failed, unknown link type.
    Link set to Full Duplex mode
    Information: throughput is limited by other network traffic.
    Good network cable(s) found
    Normal duplex operation found.

    Web100 reports the Round trip time = 77.24 msec; the Packet size = 1260 Bytes; and
    No packet loss was observed.
    C2S throughput test: Packet queuing detected: 100.0%
    S2C throughput test: Packet queuing detected: 1.05%
    This connection is receiver limited 87.77% of the time.
    This connection is network limited 12.12% of the time.

    Web100 reports TCP negotiated the optional Performance Settings to:
    RFC 2018 Selective Acknowledgment: ON
    RFC 896 Nagle Algorithm: ON
    RFC 3168 Explicit Congestion Notification: OFF
    RFC 1323 Time Stamping: OFF
    RFC 1323 Window Scaling: ON

    Server 'nitro.ucsc.edu' is not behind a firewall. [Connection to the ephemeral port was successful]
    Client is not behind a firewall. [Connection to the ephemeral port was successful]
    Information: Network Middlebox is modifying MSS variable
    Server IP addresses are preserved End-to-End
    Client IP addresses are preserved End-to-End



    That being said, I ran 3 speed tests at speedtest.net. Well, I ran 7, but, well... here's what happened:
    1. Had to try to load the page 4 times, finally loaded, test claimed to start but never gave back a ping, test never started. Waited 5 minutes.

    2. Page loaded up pretty quick, download speed went through (forgot the speed) but upload never went through.

    3. Page loaded. Download results came back really fast of 18680 kb/s. Upload results took 3 minutes but came back as 508 kb/s

    4. Had to reload the page 5 times, ran it, nothing came back.

    5. Page loaded kind of slowly, download speed came back 16112 kb/s, upload speed took 4 minutes to show up and came back as 720 kb/s

    6. Same as 4

    7. Page loaded really fast, test ran, download of 10546 kb/s. Upload speed never came back and the page says it's done.


    I haven't made any other changes at this point. Results are same/similar on my roommates computer. These connections are from the wall to the modem to the PC.
    Log into your modem and check the MTU settings and the power levels, especially the upstream.

    Your MTU is off and you have very low upload bandwidth. Could be a problem at the splitter or your modem.

  9. #9
    Downstream:
    Signal to Noise Ratio - 36 dB
    Power Level 2 dBmV

    Upstream:
    Power level - 42 dBmV


    I don't know how to check or change the MTU.
    Are these settings that could be causing all the problems? And what could have changed these, as everything was working great up until Friday and no one else could have changed anything.

  10. #10
    everything has... magically, i guess... started working again. The craziest part is 2 hours ago it was worse than terrible, i got offline for a while, came back, and it was working fine... crazy.

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