Not going to custom thank you page URL on iPhone only

When testing this page it works fine from desktop browser, going to my custom thank you page.

But when trying to use the form on a mobile device (iPhone) in Safari (or Firefox), it uploads the file but does not go to my custom thank you page, it just shows this warning "Safari/Firefox cannot open the page because the network connection was lost".

I have tried several times and get the same result.

I have also tried using just the standard built in JotForm "Thank You" page, getting same error.

I have checked your form and indeed, you have set up a custom Thank You page, when I test on an iPhone 6 Plus I went successfully redirected to the Thank You page: 

I have attached a file too, could you please check and let us know if the issue still persists on your end? 

We will wait for your response. 

OK, now it is working. No idea why now. Thanks.