Apple ID verification failed several times

"Apple ID verification failed several times: How can I set on properly my Apple ID if at each time I sign in verification failes?"

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Is this a Used Device?:

If this is a used device, then the person currently signed in to the iPhone needs to log themselves out of it. Elsewise, it is useless to your account. This is the site the seller should have used, prior to selling it to you: What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support. The seller should have known better. So, return it, requesting that they log out of it.

Some things you can try. Do you have access to another WiFi network where you can try? That has worked for several people.

Try a restart.

Restart your iPhone, iPad, or iPod touch    *

Try a forced restart. See the section towards the end of the article.

Reset Device. -

If necessary

Hard reset.     -

Do a backup and try a factory reset. Then restore from the backup.

Restore to Factory setting.      *

Restore - If you see an error when you update or restore your iPhone, iPad, or iPod.   *

Backup - Restore your device from an iCloud or iTunes backup.     *

Maybe you can set as following steps:

1:Turn on your iPhone and tap Settings

2:On the Settings interface, click on Wireless LAN

3:On the Wi-Fi interface, click the exclamation mark behind wifi

4:Enter wifi details, click Configure DNS

5:Enter the dns server interface, click Manual

6:Manual interface click to add server

7:Enter the following dns server address and click save

Thanks.