I experienced the same, same month as well. I think i figure it out after a little battle. So your created username wifi is were the data count However you have 2 other options to avoid this Use "xfinitywifi" or "XFINITY". This wont go against your modem. Make sure that all of your devices are not checked as "auto connect" on your wifi network, but the other 2 i mention (specially the cell phone). Hope that helps.
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