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Thread: Cable modem keeps dropping signal

  1. #1
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    Cable modem keeps dropping signal

    I have Optimum Online with the VOIP service as well. I have been having such a hard time getting this crap to work it's insane. I had a tech at my apartment every day last week, and they finally ran a whole new line from the outside drop box to the inlet, and then a 3 way splitter 5-1000MHz with the 3.5dB leg to the cable modem, and one 7.5dB leg to each TV. One TV has a DVR box, and one just has the wire right from the wall into the TV, no box. It seemed like everything was working, and my friend and I were playing on XBOX Live, and in the middle of a game my cable modem dropped. (by the way this was my 3rd modem, they kept replacing them thinking it was the modem before they ran the new line).

    Now I can get online for a little while, and in the middle of viewing web pages (haven't tried Live again) my cable modem will drop signal. I've gone and gotten an RCA Drop amp w/ a return path for the modem, and used that to replace the splitter, and I have the same results. I did have a 2.4GHz Vtech phone in the same room but have since unplugged it completely since they said sometimes they cause issues and since I have VOIP if the net doesn't work, neither does the phone anyway. They said sometimes the router causes issues, so while the tech was here I changed the wireless to channel 11 like he said, and I moved the router. The modem is now in the back of my closet, and the router is now 8 feet away and around a corner.

    Before they replaced the line, no matter what I did I couldn't get the modem to catch a signal. Now, if it drops, I power cycle and it's fine for a while. If I'm not on the computer overnight, I wake up, and it looks like it's been up the entire time. I do not lose connection to the router at all, only the modem drops signal. Does anyone have any idea what I can do?

    I have a Motorola Surfboard SBV-5130 modem, a D-Link WBR-2310 router upgraded to the latest firmware last night (signal has already dropped twice since this morning, once while I was typing this.) My laptop runs Vista (unfortunately), all updates installed to date.

    My modem readings with the drop amp:

    Downstream Value
    Frequency 603000000 Hz
    Signal to Noise Ratio 37 dB
    QAM 256
    Network Access Control Object ON
    Power Level 19 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 1
    Frequency 28000000 Hz
    Ranging Service ID 5831
    Symbol Rate 2.560 Msym/s
    Power Level 42 dBmV

    Signal Stats Value
    Total Unerrored Codewords 8366309
    Total Correctable Codewords 1
    Total Uncorrectable Codewords 0

    TCP Analyzer readings with drop amp
    SpeedGuide.net TCP Analyzer Results
    Tested on: 04.16.2008 13:14
    IP address: 67.82.xxx.xxx

    TCP options string: 020405b401010402
    MSS: 1460
    MTU: 1500
    TCP Window: 17520 (multiple of MSS)
    RWIN Scaling: 0
    Unscaled RWIN : 17520
    Reccomended RWINs: 64240, 128480, 256960, 513920
    BDP limit (200ms): 701kbps (88KBytes/s)
    BDP limit (500ms): 280kbps (35KBytes/s)
    MTU Discovery: ON
    TTL: 51
    Timestamps: OFF
    SACKs: ON
    IP ToS: 00000000 (0)

    Modem readings w/o drop amp, phone unplugged
    Downstream Value
    Frequency 603000000 Hz
    Signal to Noise Ratio 37 dB
    QAM 256
    Network Access Control Object ON
    Power Level 11 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 1
    Frequency 28000000 Hz
    Ranging Service ID 5831
    Symbol Rate 2.560 Msym/s
    Power Level 38 dBmV

    Signal Stats Value
    Total Unerrored Codewords 5100804
    Total Correctable Codewords 0
    Total Uncorrectable Codewords 0

    TCP Analyzer readings w/o drop amp, phone unplugged
    SpeedGuide.net TCP Analyzer Results
    Tested on: 04.16.2008 13:25
    IP address: 67.82.xxx.xxx

    TCP options string: 020405b401010402
    MSS: 1460
    MTU: 1500
    TCP Window: 17520 (multiple of MSS)
    RWIN Scaling: 0
    Unscaled RWIN : 17520
    Reccomended RWINs: 64240, 128480, 256960, 513920
    BDP limit (200ms): 701kbps (88KBytes/s)
    BDP limit (500ms): 280kbps (35KBytes/s)
    MTU Discovery: ON
    TTL: 51
    Timestamps: OFF
    SACKs: ON
    IP ToS: 00000000 (0)

    Does anyone have a CLUE what I should do? It's getting very frustrated and from here in all the cable company will do is come out with their meter like they have 8 times and tell me my signal is fine and it's the modem. I just have a hard time believing it's always the modem since this is #3.
    I GREATLY appreciate any help.

  2. #2
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    Sorry about the double post, just didn't want these readings confused with the others. My modem went out AGAIN after posting, and I took 2 sets of readings off of the modem while I was trying to restart it. Then I connected the modem directly to the main line into the apartment and took the 3rd reading.

    #1
    Downstream Value
    Frequency 603000000 Hz
    Signal to Noise Ratio 37 dB
    QAM 256
    Network Access Control Object OFF
    Power Level 6 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 1
    Frequency 28000000 Hz
    Ranging Service ID 5831
    Symbol Rate 2.560 Msym/s
    Power Level 58 dBmV

    Signal Stats Value
    Total Unerrored Codewords 8064977
    Total Correctable Codewords 0
    Total Uncorrectable Codewords 0

    #2
    Downstream Value
    Frequency 603000000 Hz
    Signal to Noise Ratio 16 dB
    QAM 64
    Network Access Control Object OFF
    Power Level -15 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 1
    Frequency 28000000 Hz
    Ranging Service ID 5831
    Symbol Rate 2.560 Msym/s
    Power Level 58 dBmV

    Signal Stats Value
    Total Unerrored Codewords 9701495
    Total Correctable Codewords 2832
    Total Uncorrectable Codewords 0

    #3
    Downstream Value
    Frequency 603000000 Hz
    Signal to Noise Ratio 37 dB
    QAM 256
    Network Access Control Object ON
    Power Level 15 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 1
    Frequency 28000000 Hz
    Ranging Service ID 5831
    Symbol Rate 2.560 Msym/s
    Power Level 35 dBmV

    Signal Stats Value
    Total Unerrored Codewords 15468443
    Total Correctable Codewords 0
    Total Uncorrectable Codewords 0

  3. #3
    Second Most EVIL YARDofSTUF's Avatar
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    honestly theres not 1 power level reading for both upstream and downstream I like of yours. LOL

    http://www.speedguide.net/read_articles.php?id=1197

    You have a couple with the downstream at 15 and -15, right on the edge liek that leaves no room if theres a spike.

  4. #4
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    It's been all over the place. A few minutes ago it kicked me from the net again, and this is the most recent reading:

    Downstream Value
    Frequency 603000000 Hz
    Signal to Noise Ratio 37 dB
    QAM 256
    Network Access Control Object ON
    Power Level 9 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 1
    Frequency 28000000 Hz
    Ranging Service ID 5831
    Symbol Rate 2.560 Msym/s
    Power Level 58 dBmV

    Signal Stats Value
    Total Unerrored Codewords 784169563
    Total Correctable Codewords 10998
    Total Uncorrectable Codewords 253

  5. #5
    Second Most EVIL YARDofSTUF's Avatar
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    You need to have them out there so they can do something to stabilize your power levels.

  6. #6
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    I put a known good splitter in the line and my levels seem to have stayed between 9 and 12 every time I've looked, mostly at 9. I've unplugged the router since 7pm last night and its now 11am, and as far as I can tell there have been no disconnects. I left am IM window open to see if it kicked me while I was sleeping and if anything did disconnect it wasn't long enough to boot Trillian offline. So it leads me to believe that my modem really IS that sensitive to the D-link router. Do you think the signal could have been causing spikes in the power level, or is that something that would be solely an issue from the cable co?

  7. #7
    Elite Member trogers's Avatar
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    Quote Originally Posted by Stevis50 View Post
    I put a known good splitter in the line and my levels seem to have stayed between 9 and 12 every time I've looked, mostly at 9. I've unplugged the router since 7pm last night and its now 11am, and as far as I can tell there have been no disconnects. I left am IM window open to see if it kicked me while I was sleeping and if anything did disconnect it wasn't long enough to boot Trillian offline. So it leads me to believe that my modem really IS that sensitive to the D-link router. Do you think the signal could have been causing spikes in the power level, or is that something that would be solely an issue from the cable co?
    I suspect there are 2 separate issues: line problem that is causing high power levels (>8 dBmV) and interference from the nearby router, causing uneven and perhaps high ping times at hop 2 of a tracert.

    The first issue needs to be addressed by getting your ISP tech in to check out the line.

    The second issue can be solved by isolating your modem a few feet away from ALL other electrical devices, including away from the router.
    "Contentment is not the fulfillment of what you want, but is the realisation of how much you already have" - anon

  8. #8
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    Tech came out again today. Supposedly everything is ok on their end. The router has been unplugged since last night. I left the modem plugged into the main inlet and all other electrical devices in the place off. There were 3 disconnects while I was out in a 4 hour timespan. I really don't know what else to do. I'm sooooo close to just ordering DSL but I don't want to lose my speed and have to pay more a month. But what good is speed if I can't stay logged in?

    I do appreciate all your help so far.

    *edit*
    I got a 5MHz-1GHz splitter to go to the modem, and a pretty expensive piece of coax to run from the bedroom closet to the wall. I have a brand new Netgear WPN824 router in the living room, so they're separated by a wall. HOPEFULLY this will work.
    Last edited by Stevis50; 04-17-08 at 08:53 PM.

  9. #9
    Elite Member trogers's Avatar
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    Check and see if the cable line from outside the house to the wall jack, and from wall jack to the modem passes near any heavy source of interference eg. heating thermostats, refrigerator thermostats.
    "Contentment is not the fulfillment of what you want, but is the realisation of how much you already have" - anon

  10. #10
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    trogers - I'm in an older apartment complex, with baseboard heating, I'm not sure where the thermostat for that is. I can't see where the line comes in outside, there is a lock box outside that they said the line feeds from. There's a crawl space under the apartment, that's where the line runs and comes up through the wall about half way through the apartment, about 8-10 feet from the outside wall, and it feeds up between the wall to where I can connect. From what the tech said, there isn't a splitter any longer. As far as I'm aware there isn't any electrical anything under the apartment, but I can't get under to see. I don't have anything electrical anywhere near the modem any longer.

  11. #11
    Elite Member trogers's Avatar
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    Turn off power to the modem for 15 mins. Then do a direct connection to the modem without the splitter and then check signal power levels.
    "Contentment is not the fulfillment of what you want, but is the realisation of how much you already have" - anon

  12. #12
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    I'm getting 15dB with just the main line.
    I was away for the weekend and when I got back, the modem was offline again. I checked my trillian history log and there were 8 disconnects between noon friday and 10am saturday, the last disconnect had to be more than an hour because trillian didn't reconnect.

  13. #13
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    Well I had a senior tech out again today. He went to the outside lock box and was out there for a little while. He said there's 2 connections on the box, and the bottom was bad. I just so happen to be linked into the bottom connection. So he moved me up to the top connection and said it should be a stable connection now. Let's hope.

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