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Thread: Internet connection suddenly vanished... then randomly came back

  1. #11
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    Re: Internet connection suddenly vanished... then randomly came back

    Quote Originally Posted by fizikz View Post
    I spoke too soon. I got a "No probe response from AP after 1000ms" message. I'll change it to 2000ms in the config file created earlier. However, I do wonder about it. 1000ms or 2000ms is a very long time for computers. Is this really the best solution?
    Yes, a long time for a computer, even an ancient one. But for negotiation-authentication between two wireless devices, not too long. Although 2000 is a bit on the higher side, 500ms is too short for that. Just compare with the usual time when a connection attempt starts through the time when you get a "Connection established" status, it will seem normal.

    Please also check -
    cat /sys/module/iwl3945/parameters/swcrypto
    if it returns "0" then try -
    Code:
    sudo modprobe -rfv iwl3945
    sudo modprobe -v iwl3945 swcrypto=1
    ..and make sure the encryption type in the router/access-point is set to WPA2-PSK only (not always necessary, but recommended; whereas WPA/WPA2 mixed mode is almost always problematic).

    However, this also seems worth noticing -
    Quote Originally Posted by fizikz View Post
    Code:
    May 14 19:20:47 ssg1 NetworkManager[1034]: <info> (wlan2): roamed from BSSID A0:F3:C1:C1:18:EA (carbon) to 00:02:6F:92:17:68 (carbon)
    If the above changes seem ineffective and this kind of messages keep re-appearing, you may try binding the SSID "carbon" with any 'one' access point of your choice by saving its mac address in BSSID field of the Network Manager setting for the connection, so that it doesn't automatically roam from one ap to another. If you need to connect to more than one (of the same SSID), you may try creating multiple such profiles with different names (although I don't know if it's effective or not, just assuming). You *should be able to* then use these profiles to switch to the ap of choice manually.

    Alternatively, you may try using 'wicd' instead of Network Manager. It often works better in these circumstances.

    To get and share a detailed diagnostic report, you may use the "Wireless Script" link in my signature. It should be able to provide some more insight into the overall settings.
    Varun
    Help others by marking threads as [SOLVED], if they are. (See how)
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  2. #12
    Join Date
    Dec 2006
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    Ubuntu 14.04 Trusty Tahr

    Re: Internet connection suddenly vanished... then randomly came back

    swcrypto=1 is confirmed.

    The router and access point are set to WPA2-PSK and not mixed mode.

    In this particular case the roaming was because I had momentarily disconnected the AP, so there was no real problem. However, it does happen that sometimes it can automatically connect to the AP which is farther away. I would like to be able to choose the AP I connect to and I have made two Network Connections with different names in Network Manager, both with the same SSID, but with the different BSSIDs (MAC) of the different APs. However, I see no way of specifying which connection to use. In Network Manager, I see the list of SSIDs but not the Network Connections I made.

    As for wicd, I believe I had tried installing it a while back and hadn't managed to get it to work. Also, I prefer to keep most core aspects of the install close to the Ubuntu defaults for simplicity and standardization.

    Your script is pretty neat. I had tried several of those commands myself previously, but here is the output of your script with more complete information: http://paste.ubuntu.com/5666538/

  3. #13
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    Re: Internet connection suddenly vanished... then randomly came back

    Quote Originally Posted by fizikz View Post
    Your script is pretty neat.
    Not my script, I just use it. It was created by people I credited in that post

    here is the output of your script with more complete information: http://paste.ubuntu.com/5666538/
    Nothing looks suspicious in there to my inexperienced eyes. However, there were a number of connection-disconnection cycles in a short interval as per dmesg part. Were you manually cycling it or was it happening by itself?

    How's the overall connection quality after increasing the "probe_wait_ms" parameter to 2000ms ?
    Varun
    Help others by marking threads as [SOLVED], if they are. (See how)
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  4. #14
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    Re: Internet connection suddenly vanished... then randomly came back

    In that instance, the disconnect errors were because the AP was being power cycled. Normally it is stable.

    After changing the "probe_wait_ms" parameter to 2000, I have not seen any drops in the last day or so. If I don't experience any more drops in the next few days, I'll consider this solved.

    Thanks for all your help!

  5. #15
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    Re: Internet connection suddenly vanished... then randomly came back

    Quote Originally Posted by fizikz View Post
    After changing the "probe_wait_ms" parameter to 2000, I have not seen any drops in the last day or so. If I don't experience any more drops in the next few days, I'll consider this solved.

    Thanks for all your help!
    You're welcome! We just try and hope..
    Varun
    Help others by marking threads as [SOLVED], if they are. (See how)
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  6. #16
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    Re: Internet connection suddenly vanished... then randomly came back

    My wireless remained stable with the Intel 3945ABG with this fix, so I'll consider this solved.

    I have tried upgrading to wireless N once again, this time by using the Intel 4965AGN adapter, and I've run into a different sort of wireless drop issue: http://ubuntuforums.org/showthread.p...5#post12672425

    However, since the drops stopped with the Intel 3945, I will mark this thread as solved.

  7. #17
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    Re: Internet connection suddenly vanished... then randomly came back

    Quote Originally Posted by fizikz View Post
    My wireless remained stable with the Intel 3945ABG with this fix, so I'll consider this solved.
    Great! Thanks for taking the time to get back to us for the feedback.

    I have tried upgrading to wireless N once again, this time by using the Intel 4965AGN adapter, and I've run into a different sort of wireless drop issue: http://ubuntuforums.org/showthread.p...5#post12672425
    Looks like Hadaka has picked up your thread. He is quite resourceful and determined, and we often keep discussing issues in the background. So you can trust him for the best kind of help we both can offer.

    However, since the drops stopped with the Intel 3945, I will mark this thread as solved.
    Yes, please do so. Follow the link in my signature to see how.
    Varun
    Help others by marking threads as [SOLVED], if they are. (See how)
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