Windows 10: Why can't I login to my work teaching platform from my pc but I can from my mobile phone?

I opened my teaching platform webpage, to login, input my details, press enter and nothing happens. I can login easily from my mobile phone. Both devices are using the same internet router. I have done a network reset and a dns flush. I am at a loss with what to do now. I have tried login in with VPN off and on, same result.I haven't used this pc for a while because I was on a work hiatus.Can someone help?Many thanksJoana

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unlock sim t-mobile lumia 521

Thanks for your suggestion, but this is a prepaid phone --- no contract. As I said T-Mobile lists the number under an unknown carrier and suggested I contact Microsoft.

 

Supported phones for Windows 10 Mobile Insider Preview Mobile

Your list confirms my phone is eligible, Lumia 521. The windows Insider App fails after ~ 15 seconds, restores data and gives me error 80073cf9. I trouble shot this and went thru all the steps mentioned on several websites including MS without any luck. Short of a hard reset, this is where I am now. Suggestions appreciated.

 

Phones and their Thinness....

Yep Indeed. Look at THIS Phone. With a 7060mah Battery! Though the Cameras are not great but that Battery Life

Just Note before buying... Phones from China only work with AT&T, T-Mobile, and Others except Verizon and Sprint