Diagnostic screen problem! No internet. Help please?

Hi there BB Guru.
I have a problem with my BB Z10 ATT unlocked, OS 10.2.1.3247
I off mobile conection and turn on Wi-fi
serf the internet, then off wi-fi and turn on Mobile connection.
But my 4G connection doesn't work. a see 4g. and no internet over celullar
But if i turn on wi-fi, with active mobile connection, after serfing internet and off wi-fi connection i have a data over the my celullar

I go to Diagnostic screen/General Radio
and i see "Modem Reset Required?" set YES.

As i understand this is the problem.
How can i fix this problem?

please help!!!

Check your apn settings.

Posted via CB10

It's under cellular, then at the bottom click the apn button
Attachment 363300

Posted via CB10

Hi friend!
All is ok as you write me! see pictures.

And new problem detected^
IF i reload my Z10 - internet is closed!