PITTSBURGH (KDKA) – If you have an older iPhone or iPad, you’ll want to update to the latest iOS before Sunday.

Otherwise, you won’t be able to connect to use certain functions.

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It has to do with a GPS clock reset that happened back in April.

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The update affects iPhone 5-S and 4-S models, as well as iPad 2-S, iPad retina display and the fourth generation iPad.

If you don’t update your iPad or iPhone by Sunday, you’ll have to connect it to a computer and do the update manually.

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To find out if your device is up to date, visit Apple’s website.