April 13, 2017 -  Sierra Tel has identified the problem with the ZyXel HN51 modem and has a solution.
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If you have this model modem and you do not have internet service please bring your modem into our Oakhurst or Mariposa business office for repair.

Once your modem is ready to be picked up we will call you; this could take an extended period of time due to the volume of repairs. Thank you for your continued patience and graciousness.
Source: Sierra Tel