iPad hangs on for dear life to an AP and fails to roam

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I have a small school that have 30+ AP121's and we have a number of iPad’s that move between classrooms and they cling on to the initial AP for dear life and only move once they have been threatened with violence. Any tips on what I can do to improve this?
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Chimptastick

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Posted 5 years ago

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Adam Conway

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If you have a reasonable density of APs (1 per classroom or 1 per 2 classroom) turn off data rates 1, 2, 5.5, 6 and 9. If you are positive that you don't have any .11b clients, turn off 11 as well. Set your new lowest rate to be the basic rate. This will prevent clients from connecting from a long distance. Rates can be found in the SSID object.

Also, IPads are not known to be overly sticky (to my knowlege) so also make sure that the "ESS" stays the same across all devices. The easy way to ensure this is to run one "Network Configuration"
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Chimptastick

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Excelent thanks for your help I will try this now.
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Adam Conway

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I failed to give you the big caveat - this does decrease range, but also will give much better performance over time. The lower datarates go further, however consume more airtime slowing down the network. I want to make sure that you understand this tradeoff. If your teachers are used to going outside and connecting to an AP inside, they may be disappointed.
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Chimptastick

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Understood, that is not a problem, We have 1 AP per classroom an i still have the radios set to Auto. my next step was to start manualy turning them down. We try not to let anyone outside the buildings in central London!
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Crowdie, Champ

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Two other factors for you to consider:

1. Radio power. If you have the 2.4 GHz maximum radio power disabled or set to 20 dBm in the radio profile then the 2.4 GHz wireless clients will have a tendency to become "sticky" (not want to roam). I have found that using a combination of reducing the maximum radio power, disabling the lower speed data rates and raising the lowest mandatory (or Basic) data rate seems to work best.

2. Don't put access points in long corridors or walkways. This is for two reasons:

* When you put an access point in a corridor and a wireless client moves away from the access point down the corridor there is a small signal loss, called free space loss, as the signal only has to pass through the air. If the same wireless client walks five rooms down the corridor and then suddenly enters a room the signal suddenly drops significantly as it now has to pass through all the walls, furniture and other obstructions in the room to get to the access point. Low powered devices; such as iPads, iPhones and Android devices; can hate this sudden change from very high signal to very low low signal and disconnect or stay connected but have little to no throughput. On an iPad you can see this in the WiFi section of Settings as instead of showing the signal strength in bars it shows a rotating dial. I have seen iPad 2s stay in this state for 2-3 minutes before restoring connectivity.

* Access point listen for neighbouring access points and if they are on the same channel they will adjust their channel/power settings to avoid interfering with the neighbouring access point. When you put access points in corridors their signal can go huge distances down the corridor and affect other access points in the corridor. So you have nicely site surveyed the building with a single access point and placed four access points in the main corridor. When the access points are powered on the 2.4 GHz radios only have three channels to choose from (1,6 and 11) so two access points must be on the same 2.4 GHz channel. These two access points on the same channel detect each other and reduce their 2.4 GHz radio power to avoid interfering with each other. That reduced radio power can now introduce coverage holes that weren't there in the site survey.