Loss of internet connection to my mobile phone. My main computer still has good connection.

[SimonT16]

I go to Settings and press Network and Internet. I press Internet Networks available. TALKTALK9A3E11 is displayed. with Authenticating, followed by  Saved/Can't connect. Try again later.

I have tried pressing Forget and re-inserting the Router password, then pressing Connect which shows Fair Signal Strength but again it says Authenticating ,/ Can't connect.

My phone technician believes the problem is with the Service Provider and not with the mobile phone itself.

Please help my mobile to re-connect.

[Arne-TalkTalk]

What make and model is the phone?

[SimonT16]

Any further advice?