Cant add yahoo in mail

Greetings Lhvp1927,

Contact your email service provider for additional assistance if you are unable to add the account manually to your iPhone. Since it appears that you're unable to load the website using Safari and Chrome as well, they'd be the best hands possible to look into any issues on their end. However, we do have some steps we can try. Check out those steps here:

Add an email account to your iPhone, iPad, or iPod touch - Apple Support

"Enter account settings manually 

If Mail can't find your email settings, then you need to enter them manually. Tap Next, then follow these steps:

1. Choose IMAP or POP for your new account. If you aren’t sure which one to choose, contact your email provider.
2. Enter the information for Incoming Mail Server and Outgoing Mail Server. Then tap Next. If you don't have this information, try to look it up.
3. If your email settings are correct, tap Save to finish. If the email settings are incorrect, you'll be asked to edit them. 

If you still can't set up your email account or save your email settings, contact your email provider."

Kind regards.