Internet disconnects and won't reconnect until restart

By gildedarmour
Feb 21, 2014
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  1. I've been having this problem for only the last week or so where my internet will stop working until I restart my computer, even though it says I am connected and internet is available.

    The problem is not with my modem or my router. The internet works fine on every other computer.
    I've run multiple antivirus scans on multiple programs. Clean.
    Drivers are up to date.

    Sometimes it disconnects after five minutes, sometimes forty, sometimes hours.
    I'm at a loss. Any ideas?
  2. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    What is this computers make and model? How does it connect to the Internet?
  3. gildedarmour

    gildedarmour TS Rookie Topic Starter

    I dont know the model. All it says is "To be filled by O.E.M"
    This is a computer I had built for me.
    It connects with ethernet cable.
  4. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    "I've run multiple antivirus scans on multiple programs. Clean"... How many "antivirus" programs do you have installed. What are these programs... the names?
  5. jobeard

    jobeard TS Ambassador Posts: 9,317   +618

    When it disconnects get us some information:

    get a command prompt (start->search, enter CMD and press return)
    then enter
    ipconfig /all >myTCP.txt
    open that file, copy all the content and paste it back into your follow-up reply.

    I suspect you're loosing the DHCP server
  6. gildedarmour

    gildedarmour TS Rookie Topic Starter

    Avast and microsoft security essentials. and aight I'll try that next time it goes down. I also just rebuilt my computer from scratch and that didn't solve it. :(
  7. Tmagic650

    Tmagic650 TS Ambassador Posts: 17,244   +234

    "Avast and Microsoft security essentials"... Pick one only and completely un-install the other! Then do what jobeard said
  8. gildedarmour

    gildedarmour TS Rookie Topic Starter

    I only had one installed at a time.

  9. jobeard

    jobeard TS Ambassador Posts: 9,317   +618

    Default Gateway . . . . . . . . . :
    DHCP Server . . . . . . . . . . . :
    those are quite normal - - pointing to your router.

    Have you power-cycled that router {recently or ever}? Do so. wait at least 30 seconds before restarting it.

    When the symptom reoccurs, get the command prompt again and enter
    you should get back
    IPv4 Address. . . . . . . . . . . :
    Subnet Mask . . . . . . . . . . . :
    Lease Obtained. . . . . . . . . . : Monday, February 24, 2014 6:20:37 PM
    Lease Expires . . . . . . . . . . : Monday, February 24, 2014 7:50:38 PM
    Default Gateway . . . . . . . . . :
    THEN FOLLOW with
    and lastly

    you should have the default gateway dhcp & dns addresses again.

    If not, then there's a problem in the router
  10. gildedarmour

    gildedarmour TS Rookie Topic Starter

    And assuming it works, that should fix it permanently? Like, it won't keep losing internet and I'd have to type that stuff in?
  11. jobeard

    jobeard TS Ambassador Posts: 9,317   +618

    "should fix it permanently?" Hmm. Even when you have a hair permanent, you still go back again - -
    The Rock of Gibraltar might be, but I would never call anything with computers permanent :sigh:
    Last edited: Feb 25, 2014
    learninmypc likes this.
  12. gildedarmour

    gildedarmour TS Rookie Topic Starter

    Ok so, when I did that I got up to ipconfig /renew but when I entered that command, a line popped up and said "Windows IP Configuration" and I couldnt enter anything else.
  13. gildedarmour

    gildedarmour TS Rookie Topic Starter

    Oops, and then a few minutes after that it says "An error occured while renewing interface Local Area Connection : unable to contact your dhcp server. Request has timed out."
  14. gildedarmour

    gildedarmour TS Rookie Topic Starter

    Fpfpffpffft ok I reset my winsock and then tried it again when I lost the internet and it worked this time. everything is the same as it was before soooo, does that mean the problem isnt fixed?
  15. gildedarmour

    gildedarmour TS Rookie Topic Starter

    Yeah ok I lost connection again 2 minutes after I did that. so its my router, then?
  16. Philip Booth

    Philip Booth TS Member

    Perhaps you need to extend the main memory, I guess that your computer run number of heavy software together with internet.
  17. gildedarmour

    gildedarmour TS Rookie Topic Starter

    I was one tab of youtube and google when it shut down that time. Why would it be the memory? I've never had a problem before this last week and a half.
  18. jobeard

    jobeard TS Ambassador Posts: 9,317   +618

    NO! it's not memory.

    You have two different issues
    1. frequent disconnects
    2. failure to honor a release/new cycle
    Let's talk about your ISP connection - -
    WHO is it and what type {Dsl, Cable, Satellite} ?

    DSL has special considerations which requires a filter on every device connected to the phone line OTHER than the modem. This is a direct contributor to the disconnect problem (*IF* you're using dsl)

    You ought to get the make/model number of the router and look for a firmware update (regardless of {Dsl, Cable, Satellite} as you ought to be able to renew).

    Here's a test you can run to determine if your router needs to reassemble packets:

    get the command line and enter:
    ping -f -l 1500​
    the character between the -F and google is an ELL in lower case.

    My results are:
    C:\Users\Jeff>ping -f -l 1500
    Pinging [] with 1500 bytes of data:
    Packet needs to be fragmented but DF set.​

    Now repeat that test by reducing the 1500 by -8 until it replies
    C:\Users\Jeff>ping -f -l 1440
    Pinging [] with 1440 bytes of data:
    Reply from bytes=1440 time=18ms TTL=53​

    My test of the value just above that produced:
    C:\Users\Jeff>ping -f -l 1448
    Pinging [] with 1448 bytes of data:
    Request timed out.​

    When packets get fragmented, the router needs to do extra work and not only is that a performance hit, but also a vector for network virus' - - so help the poor thing along by setting the MTU in the router itself.

    Set the MTU to the highest value that replies with times and does not timeout.
  19. lpenny22

    lpenny22 TS Rookie

    Thanks jobeard! That works beautifully! It even seems like the internet is faster!!! I'm a networking study monger now! :)
  20. Jobeard,I was having the same issue.Internet disconnecting for no apparent reason.Tried your solution (ipconfig commands) and it worked! Thanks very much.
  21. I'm having the same problem. However, when I try this process above, I get "Packet needs to be fragmented but DF set" when I ping 1394, but "Request timed out" when I ping 1394.
    I'm also getting a DCLhelper error message when I restart my computer. Don't know if it related.
  22. Sorry, I meant 1395 then 1394.
  23. jobeard

    jobeard TS Ambassador Posts: 9,317   +618

    Both values shown are incorrect; the maxMTUvalue must be a multiple of 8
    1304, 1392, 1400, 1408

    The ping should read
    ping -f -l maxMTUvalue somesitename ## the 3rd parm is lower case L
    eg ping -f -l 1492

    The correct place to set the MTU is in the router, which will protect all systems attached to your router.
    Another guest suggested which alters just one pc
  24. Martin2648

    Martin2648 TS Rookie

    I'm having a similar problem and would like to ask if the same methods can be used here as described before. The thing I'm getting is that when I'm playing online game randomly my Internet cuts out. The strange thing is that the icon on the work bar says that the Internet is still coming in and even the connection with the game remains normal. However opening pages in browsers, loging in to steam or other launchers or basically a tempting to create new Internet connections fails even if whatever games I connected to before this randomly happens still remain open. I tried to switch my connection from my virgin media router to a hotshot on my phone that is network 3 but it won't create any new connections and the pc has to be restarted. This makes me wonder if doing anything to the router would help if switching connections has no effect until restart.
  25. jobeard

    jobeard TS Ambassador Posts: 9,317   +618

    The MaxMTU will never hurt any system, so give it a try...

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