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If your iPhone, iPad, or iPod touch won’t connect to a Wi-Fi network - Apple Support. Click here --> https://support.apple.com/HT204051

March 2019, other tips by Lawrence Finch:

https://discussions.apple.com/thread/250213083?answerId=250395509022#250395509022

If you can't activate your iPhone - Apple Support - https://support.apple.com/HT201407 - "If your iPhone can't be activated or an alert says the activation server is unavailable [or cannot be reached] or the SIM card is unsupported, learn what to do."