Hi @Lalo77, welcome to our forum and I'm sorry to hear about this. 
I can see that your question has been translated to English since this is a English only forum, please post your future questions / feedback in English! 
If I understand correctly, the phone restarts when you enable Wi-Fi, is that correct? If that is the case, try restarting your phone in safe mode and see if you experience the same behaviour when third party applications aren't loaded.
Let me know how it went!
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