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Old 05-24-2017, 07:29 AM   #1
kudsu
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Question why does this work?


Now I have one of those internet services that is ADSL. I use to have Time Warner but got rid of them because the service was unbelievably poor. I have been having a problem with outages but it seems to pop back in when I run:

sudo iwlist wlan0 scanning

This almost always works.

I would guess that this resets the wireless handshake but I don't know.

Does anyone really know.

Thanks again.
 
Old 05-24-2017, 08:52 AM   #2
bigrigdriver
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I don't know why it works.

I think you would have more consistent results in bringing the network back up if you used the ifup command.

sudo ifup wlan0
 
Old 05-24-2017, 02:28 PM   #3
ondoho
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how your wireless works has nothing to do with your ISP.
(i doubt they provide wireless to you???)
 
Old 05-24-2017, 04:24 PM   #4
rknichols
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Quote:
Originally Posted by ondoho View Post
how your wireless works has nothing to do with your ISP.
(i doubt they provide wireless to you???)
Actually, ISPs often do supply you with a gateway device that combines the functions of modem, router, and wireless access point. Historically, the WiFi performance of those devices has often been sub-par. I try to avoid those combo devices like the plague, but with ADSL you might not have a choice.
 
Old 05-24-2017, 04:37 PM   #5
jefro
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Not sure we have been told how you decided what part of the chain is failing. What tests have to performed to try to locate the issue?

I would totally agree that most ISP's stink. I'd agree that a home modem provided by an ISP could have issues. Almost anything between the isp and your system could be at fault unless you track the location a bit better.
 
Old 05-24-2017, 06:50 PM   #6
scasey
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Based on what man iwlist says, I'd guess that works because it asks the wireless interface to
Quote:
Give the list of Access Points and Ad-Hoc cells in range, and optionally a whole bunch of information about them (ESSID, Quality, Frequency, Mode...). The type of information returned depends on what the card supports.
and that scan "wakes up" your wireless NIC.

But that's just a guess.
 
Old 05-25-2017, 07:04 AM   #7
rtmistler
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Likely it works because you already have a selected network.

You shouldn't be scanning for networks, you should be using iwconfig to view the interface and use the ip(8) command to control it.

Alternatively if you are using a desktop, there may be a wireless device network manager. Perhaps the distribution and (if any) desktop environment you're using will be helpful for us to give you better advice.

I agree with others that it is not the ISP service, but likely the WIFI router. Checking the connections for it, knowing the model of it, as well as where you have it located with respect to the problems you're experiencing will be helpful. If you have a dead spot or series of them in your living area, perhaps moving the WIFI router to another location is a better option. There are also amplifier with better antennas you can get to help extend your range. The WIFI router my ISP gave me is an 11n, but it has a single antenna. This is bad to the level of what they call "diversity" where the router having two antennas can multiplex signals or split the functions of the antennas to allow for better performance. Thus we can suffer degradation to our signal during high traffic times.

You may also wish to look at the settings and see if 5.8 GHz works better than 2.4 GHz, or if that even is an option with your desktop as well as your router.
 
Old 05-25-2017, 07:40 AM   #8
kudsu
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Smile Better info

This is a Centurylink ZyXEL combination modem and router model #C1100Z. The network manager is the one that ships with Linux Mint 17.3 mate version. It is always a joy to hear that I have been treated to the most bizarre and crappiest equipment. I tried the arp command but this only shows two devices, there are maybe 10 or more. Ifconfig works normally.

I called Centurylink when this laptop was offline according to the network manager. I was told by the guy he could see the device the laptop and it was online. Clearly it wasn't. He fooled around with it a little bit and it started working. No science no clue just started working.
 
Old 05-25-2017, 08:20 AM   #9
rtmistler
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Sorry but I'm still hearing that it went "offline" but no real details.

Are you moving it around? Is it going to sleep, power saving, hibernation and then when it wakes up is it not automatically re-attaching to the network?

What are the signal levels you are seeing? What connection type do you have and speed? For instance, do you get an actual 11n connection, or does it get degraded to 11g or 11b? What data rate is it saying you have when it is connected?

How far away from the A/P are you? How many construction elements (walls and floors), or machines and electronics are between you and this A/P?
 
Old 05-25-2017, 02:28 PM   #10
kudsu
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wlan0 IEEE 802.11abgn ESSID:"CenturyLink3918"
Mode:Managed Frequency:2.452 GHz Access Point: 60:31:97:4A:3F:B0
Bit Rate=65 Mb/s Tx-Power=15 dBm
Retry short limit:7 RTS thrff Fragment thrff
Power Managementff
Link Quality=70/70 Signal level=-40 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:74 Missed beacon:0
 
Old 05-25-2017, 02:50 PM   #11
ondoho
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^ yeah, just dump some random command output without any context, when asked to provide details.
not even in code tags.
 
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Old 05-25-2017, 04:36 PM   #12
kudsu
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Sorry O. I have PD and was only able to copy and paste the above. The command was iwconfig wlan0. The laptop is located directly below the access point. Their is ceiling joists, drywall, carpet, etc in the way. The other tablets we have have a problem with signal as well. The router is upstairs near the bedrooms and there are no computers up there.

The only way I was able to tell that the laptop was offline was the icon on the network manager for Mint 17.3 mate. It goes from bars to a symbol that I think is supposed to be disconnected. You can also expand network manager and see when the access point is greyed out and offline ( I think). I have no O scope or meter. Thanks again.
 
Old 05-25-2017, 05:28 PM   #13
Shadow_7
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I would imagine that it would reset any powersaving mode when you run iwlist. Although your output seems to suggest that it's off (on at least one side of the equation). Otherwise it could force the lease to renew. There's probably details in the logs when you have issues. But wifi is subject to a lot of things. At my dad's house, when the convection microwave gets used, it kills the wifi. Back in the day of cordless phones, they were on roughly the same frequencies as the wifi. These days your LED lights are probably putting off interference and many other things that occupy that same spectrum like active radar systems. It could also be that iwlist is doing little more than buying time for the system to recover or the interference to stop. I mostly issue pings when I have issues and it goes away.

$ ping -c 2 192.168.1.1 && ping -c 2 8.8.8.8

The first one to make sure the router is responsive, aka the home network, the second to see if google dns is available, aka the internet. There's iw now, iwconfig is the OLD way, but probably still works as long as you have it installed.

$ sudo iwlist wlp1s0 scanning
$ sudo iw dev wlp1s0 scan

Perform basically the same function.
 
  


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