The request from the Public Feed failed

Hello,
I installed your plugin in the localhost and it works!
But when I installed it on my online website doesn’t work and I get the following error:

Instagram Widget misconfigured, check plugin & widget settings.

The request from the Public Feed failed. Check username.
The request from the Public Feed failed. Invalid server response from Public JSON API url.
Get items from the Public Feed failed. Invalid response.

I tried it on 3 different websites and hosts, but I got the same error.

Please help me to fix this problem.

Thanks