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  1. #1
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    I have a laptop running Vista and a PC running XP on my home network. Both are wired to the wireless router that allows us to connect to the Internet. Occasionally (maybe 30% of times), after waking up the laptop from sleep mode the laptop can no longer connect to the Internet. I have tried running network diagnostics and any other fix-it features that are provided in Vista and none of them can correct the problem. The only thing that corrects the problem is to unplug the router's power and plug it back in. However, the PC can connect to the Internet during the time that the laptop cannot so obviously the router has not stopped working completely! When I reboot the router I don't have to do anything on the laptop; the email program or browser simply can connect afterwards.

    Today, I enabled the laptop's wireless connection and tried to connect that way without rebooting the router but that didn't work either. The wireless status said "Local Only". Maybe that is a clue as to what is wrong.

    Any ideas as to what is wrong or how to troubleshoot this problem will be appreciated.

    Thanks, Bill

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    Quote Originally Posted by BillWilson View Post
    The wireless status said "Local Only". Maybe that is a clue as to what is wrong.
    Yep, That is almost always a problem with the way the DHCP server in the router is handing the IP address information out to the laptop. Does it only do this when coming out of sleep mode?

    What happens if you issue an
    Code:
    ipconfig /renew /all
    at the command prompt when you get the above message? It might also work to go into the network screen on the laptop and disable and then re-enable the wireless connection.

    Let us know the results of either of the above and we will see if we can figure out how to fix the underlying problem..

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    The DHCP server should not be a problem, your laptop will happily maintain the existing IP address.

    Do you have SSID broadcast turned off on the router? If so, turn it back on.

    cheers, Paul

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    mercyh: One of the diagnostic tools that surfaces when there is a network problem is a popup that will renew the IP address if you click on it and I've done that a number of times in the past but it didn't help. I'll certainly do the ipconfig /renew /all the next time the problem occurs to see if it will help.

    Paul: I do not have SSID broadcast turned off. Don't forget, I normally don't even use the wireless capability when I am at home. I'm guessing that the SSID broadcast is a wireless characteristic but maybe I'm wrong about that.

    I have read in the past about people having problems with not getting their network connection back after coming out of sleep mode but I don't loose it every time and I wouldn't think rebooting the router would fix that problem if I did have it.

    Thanks for your suggestions.
    Bill

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    One of the diagnostic tools that surfaces when there is a network problem is a popup that will renew the IP address if you click on it
    Another one of windows diagnostics also disables and then enables the network adaptor which should fully renew the address and remove the adapter's mac address from the router's DHCP table. If you have run the renew tool above I don't think the command I gave will do the trick.

    The reason I am suspicious that you are not retaining your IP settings through sleep is that the message you are getting indicates that the Gateway or DNS server entrys are not correct. If for some reason your machine loses the setting without actually disconnecting from the router, sometimes the router will show an IP address handed out to your machine in its DHCP clients table and so will not hand another one out.

    Another problem I have seen with Vista and 7 clients is that for some reason they will see the wireless network as an "unknown" network (even after being connected multiple times) and yet will not ask the "Public, work or home" question. I have not figured out what causes it but it seems to be some routers do not play well with Vista or 7.

    You can check this by going into "network and sharing center" and under "view your active networks" see how the network is labeled. (it should be home, work or public)

    Are you having this problem with the laptop both wireless and wired??

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    Quote Originally Posted by mercyh View Post
    You can check this by going into "network and sharing center" and under "view your active networks" see how the network is labeled. (it should be home, work or public)
    It is currently listed as a public network.

    Are you having this problem with the laptop both wireless and wired??
    Well, almost all my experience has been with it wired but I ahve switched to wireless once or twice to see if that would work and it did not when I tried it earlier today.

    Thanks, Bill

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    Is it currently working with the 'Public' setting?

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    Well, almost all my experience has been with it wired but I ahve switched to wireless once or twice to see if that would work and it did not when I tried it earlier today.
    This cuts wireless out of the equation as it happens on both wired and wireless connections.

    When you have the problem can you access shares on your local network?

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    A note about the router and DHCP. Routers (DHCP servers) do not care whether the MAC address is in the client table, a DHCP response is always provided and the IP address is either the one in the client table, or new if none exists.

    Bill, I missed the bit about it being hard wired.
    When it next doesn't connect, open a Command Prompt and type ipconfig /all. This will tell you the current state of the network card.
    You can then try renewing the IP address by typing ipconfig /renew.
    Let us know the result.

    cheers, Paul

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    Quote Originally Posted by P T View Post
    A note about the router and DHCP. Routers (DHCP servers) do not care whether the MAC address is in the client table, a DHCP response is always provided and the IP address is either the one in the client table, or new if none exists.
    I have seen two real life scenarios where this does not work correctly. In the first the DHCP server is too smart and in the second the DHCP server is too dumb.

    1. Client disconnects from the network and for some reason is not cleared from the DHCP clients table on the DHCP server. It then reconnects and asks for a new IP lease. The DHCP server compares the MAC address to the list of clients and refuses to give it a lease as it shows it has already been assigned an IP address. (I fought this situation for several hours one day until I found that I had to clear the DHCP client entry on the DHCP server and then reset the NIC on the client before it would obtain an address.)

    2. Clients are connected to switches (not directly to the router). The router is rebooted but the clients do NOT reset their network connections as their connection does not power down with the reboot. As clients are rebooted or new devices are brought onto the network the DHCP server begins handing out addresses at the BEGINNING of its address range as it no longer knows about the clients that already have these addresses because its client table has been flushed. Suddenly devices begin to lose connection with the error that the IP address is already in use. A smart DHCP server will ping an address before leasing it out, almost no consumer grade devices have this feature.

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    Paul: I'll try the ipconfig /renew the next time it fails and see if that helps but I doubt that it will because using the network diagnostic thing to get a new IP address has not helped when I've tried that a couple of times in the past.

    merchy: The next time this problem occurs I'll see if I can still access a folder on the other PC on the network. The problem with this is I frequently lose access to the other PC on the network! For example, I can't see the other PC right now. I don't know if this is related to going into and out of sleep mode. When I need to connect to the other PC for backup purposes I reboot both computers and it always can connect then.

    Does a computer normally retrieve a new IP address after waking up from sleep mode? In other words, is waking up equivalent to rebooting with respect to IP requests?

    Thanks for the suggestions.
    Bill

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    Does this usally (or always happen after resuming from sleep mode)? How long does your computer remain in sleep before this happens?

    I "think" (and this is an assumption) that the adapter will not renew the address after sleep, I "think" it will try to resume in the same state it was in when it went to sleep...

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    I would like to eliminate the whole DHCP thing as a vector in this problem. Would it work for you to temporarily assign static IP addresses to all your machines and see if the problem goes away?

    When you have the problem is the network listed as "private" or is it "unknown" ?

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    The amount of time in sleep mode varies widely from one time to the next. I tend to leave my laptop on all the time and it is set to go into sleep mode after 4 hours. So, it goes to sleep occasionally during the day and usually during the night. There are some days when I get to the laptop in the morning and it is not in sleep mode! I don't know why that happens either. I use Carbonite for backup. Would internet activity by Carbonite prevent the laptop from going into sleep mode?

    I'll look at assigning fixed IP address during the next few days and see what happens.

    Thanks, Bill

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    Bill, the ipconfig commands will tell us what your computer is doing. Using "repair" does the same thing but doesn't give us a nice bit of text to look at.

    mercyh, The DHCP spec is clear about the expected request/response.
    1. All requests will receive a response, either the currently allocated IP address or a new one. In either case the DHCP server updates the lease time.

    2. If the router does not maintain a non volatile copy of the database it is not performing it's job properly and should be thrown in the bin.
    A DHCP server can be configured to ping an address before providing a response, not because it is "smart". This delays the response and should be avoided, especially in a busy environment.

    cheers, Paul

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