Unable to pull images: Network timed out while trying to connect to

Hi all,

I have seen several issues like this one, but it looks like I’m not in the same situation.

Firstly, I work on windows.
My docker version is 1.10.2.
And I am behind a proxy.

So, I just connect to the “default” VM and add the following environment variables:
HTTP_PROXY, HTTPS_PROXY, http_proxy, https_proxy.

Then running the following from the VM:
docker run -it ubuntu

Finally returns:
docker: Network timed out while trying to connect to https://index.docker.io/v1/repositories/library/ubuntu/images. You may want to check your internet connection or if you are behind a proxy…

Which is very strange (for me) because
curl https://index.docker.io/v1/repositories/library/ubuntu/images
works fine…

Any help would be very appreciated.