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Wireless Network

Posted on 2014-01-19
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Last Modified: 2014-01-20
I have a wireless network set up at the church I work at and it works well majority of the time.  But I am running across some instances that I cannot figure out.  The 2.4GHz wireless network sometime will not connect to wireless devices.  Some laptops people have brought in will connect but show they do not Internet access, or they will not join the network at all.  At the same time I will have iPhone, iPads, and other computers connected to the network and working fine.  This specific router sends out two networks a 2.4GHz network and a 5.0GHz network.  Sometimes when a device cannot connect to the 2.4GHz network it will have not problem connecting to the 5.0GHz network.  Can anyone tell me why I am having this difficulty and what I can to to solve it.  

I am also running a guest network on the 2.4GHz network.


Here are the detail on the router:

Amped Router

System Status




Internet Connection Status
Internet Connection Type:
      
Fixed IP Connected

5.0GHz Wireless Network Settings
Band:
      
5 GHz (A+N)

Channel Number:
      
36
Encryption:
      
WPA2 Mixed

Associated Clients:
      
2
2.4GHz Wireless Network Settings
Band:
      
2.4 GHz (B+G+N)

Channel Number:
      
1
Encryption:
      
WPA2 Mixed

Associated Clients:
      
4


Local Area Network Settings
Router IP Address:
      
192.168.0.1
Subnet Mask:
      
255.255.255.0
Default Gateway:
      
192.168.0.1
DHCP Server:
0
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Question by:Bill2802
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18 Comments
 
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Expert Comment

by:Dave Baldwin
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Modern wireless networks work fairly well up to about 25 users.  After that mutual interference starts becoming a problem.  Mutual interference is where the devices are creating so much radio noise that they interfere with each other.

How many users do you have when there are problems?  Have you checked the neighborhood for other wireless networks that might interfere?
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by:Dave Baldwin
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I use WirelessNetView to see what other networks are operating in my neighborhood.  In my apartments, it can be over 20 other networks.

http://www.nirsoft.net/utils/wireless_network_view.html
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Expert Comment

by:akahan
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You may want to increase the number of DHCP addresses being handed out by the router, so that it can handle more users simultaneously.  What is the DHCP address pool set to?  Can you provide some idea of how many distinct devices try to connect over the course of a day?

As well, the leases being handed out by your router may be too long.  If you have a limited number of DHCP addresses to hand out, you don't want the addresses continuing to be "reserved" by a particular device long after the device has left the building, as it will be unavailable to anyone else.  If you have high device turnover (people/devices entering and leaving the network continuously), then you want the router to hand out very short leases...perhaps an hour, rather than a day.

If you turn the router off and back on, and all of a sudden devices which couldn't connect a moment ago can suddenly connect, that suggests that you are running out of DHCP addresses to hand out either because the pool is set too small, or the leases are set too long.

As well, some devices may not be able to connect, ever, because their NIC drivers don't speak WPA2.  Generally, updating the network driver in the device will help there.

If you are finding that someone who comes in the building with an iPad can connect when a moment ago someone with a laptop couldn't connect, that suggests a possible problem with the laptop's WPA2 compatibility, rather than a shortage of DHCP addresses.
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Author Comment

by:Bill2802
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The DHCP is handled by our server which is running MS SBS 2011.  The pool is set to he the 255 limit.  On a Sunday we will get close to this with about 150-225 devices connected.  I have never seen the entire pool used up yet, but it has come close.

I will check the WPA2 connection.
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Author Comment

by:Bill2802
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I checked active users for the 2.4GHz network and there were only 4 active clients on the 2.4GHz network when one person was trying to connect.  There were 3 active clients on the 5.0 GHz network.  The person I was having test was using an iPad Version 7.0.4 Model MC77066/A.
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by:akahan
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Doesn't matter how many active/simultaneous clients there are.  It matters how many leases are still "alive" from FORMERLY active clients.  What's the lease time the server giving out on DHCP leases?
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Author Comment

by:Bill2802
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The lease time is 6 days.  But I went in and deleted leases that I figured were on longer being used and the test iPad still was unable to log onto the 2.4GHz network.
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Expert Comment

by:akahan
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Exactly which Amped router? (model? rev #? )
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by:akahan
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And how did you "delete the leases"?
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LVL 25

Expert Comment

by:Fred Marshall
Comment Utility
There are just a few questions; some have already been asked.
The DHCP range you provide out of the wireless router should have plenty of addresses so that the number of leases does not exceed the number available.  If you have lots of transient wireless users then you will want to make the lease time short - like 4 to 8 hours - so that there won't be unused leases holding up addresses.  You want them to release the addresses often.
Your data shows how many clients have leases (it appears) but don't tell us how many addresses in the DHCP range OR the lease time.
Also, you should not have any devices with static addresses assigned within the DHCP ran ge in order to avoid conflicts.  The DHCP server will most likely not know of these and will try to assign those same addresses.

You have a guest network but on which channel?  Channel interference has to be considered.  On 2.4GHz you can use 1,6 and 11 to minimize overlap.

If the DHCP is for both 2.4gHz and 5GHz then issues as you describe aren't DHCP related.  But radio frequency propagation can be a real difference (antenna patterns, path obstacles, etc.).  walls, ceilings and floors soak up a lot of signal (i.e. attenuate).

Wireless should be implemented with a degree of overkill to be robust.  Are you sure you have that overkill?
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Author Comment

by:Bill2802
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The Amped Router is a R20000G.

I deleted the leases by logging onto the server and going into the DHCP manager and going to leased IPs and deleting the ones that I figured were not being used.

I do have the overkill.  The Amped router is our main wireless router and I have the antennas amplified.  The laptop and iPad I was trying to connect were less than 15 feet away from the router.  All DHCP is handled by our server, the DHCP is turned off on ALL our routers.  I have several access points throughout the church to provide access, but the guest network is just available in the office area and the sanctuary.
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Expert Comment

by:sgt_best
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I know this sounds simple but some older laptops will not display the SSID when it is WPA2.
Try changing to a WEP just to see if it is the device.
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by:Fred Marshall
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iPads will not accept maximum length passphrases.  I've had that happen.  There's no warning - it just won't work.  So, if you're using a passphrase that's 63 characters in length (the maximum) then the iPad won't connect.  If that's the case then I would try something shorter.  That may be a nuisance overall but necessary.
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Author Comment

by:Bill2802
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The passphrase is actually fairly short.  The SSID shows up on the laptop and as I said it will connect, but it gives the error message, "limited connectivity" and will not access the Internet which is what they are trying to do.
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Accepted Solution

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Fred Marshall earned 500 total points
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"Limited Connectivity" is almost always the message you get when the passphrase is wrong.  I can attest (and admit) that I have sometimes had to type in a short passphrase up to 6 times to get it right.  So, it's likely a common occurrence.
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Author Closing Comment

by:Bill2802
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I think that this may have been the problem.  Although not only I but another of my fellow workers had typed it in, you are right especially on a laptop you can mistype it easily.  Thanks.
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Expert Comment

by:Fred Marshall
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Thans for the points!

Sometimes I use a very long passphrase that's a random string.  (There are websites that will generate them for you).  Of course, a caution about the iPads as above.

Anyway, using a long random passphrase means a few things:
- it cannot be memorized so it must be copied and pasted.
- no typos are possible really.
- depending on how you store the passphrase (obfuscation, encoding, etc.) security of the passphrase can be better than one that's memorized and most likely written down.
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by:vivigatt
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When deleting the leases it may require the DHCP service to be restarted for the deletion to be taken into account.
6 days is certainly a long lease time (wasn't it the time your God took to create the whole universe? ;) ).
Try shorten it to 6 hours!
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