Q: iphone could not be activated because the activation server cannot be reached

I bought my son a new 6S and he had it set up but now he is locked out of it. It said he needed to set up his phone but after connecting to a strong WiFi signal it says "Your iPhone could not be activated because the activation server cannot be reached."

Besides driving the 30 minutes to the closest Apple store what can I do to get through this issue?

Thank you!