I have an Asus Zenfone 5 ZE62OKL, the 2018 version and AT&T in USA. I'm able to make phone calls and text messages but unable to connect to the internet on 4G, 3G, or 2G. It is on Oreo 8.0.0. I am using the suggested APN settings for my sim card from AT&T and still unable to connect.
I have solved the issue by updating the ZenUI system updates allowed me to pick my carrier.
- Forum posts: 1,288
Jun 29, 2018, 3:38:29 AM via Website
Jun 29, 2018 3:38:29 AM via Website
There was some likeness between my phone and yours.
My phone failed to make any calls and text messages suddenly the day before yesterday. It was also unable to connect to internet on 4G or 3G. It didn't work yet after I restarted several times. 
So I went to a customer center of my carrier yesterday. It replaced my SIM card. Now it resumes and works well till now. 
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Try to call the provider, very often it happens that they have a problem
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