Error updating or getting any modules - Proxy

I installed drupal 8 on my machine and I keep getting errors for updates

DRUPAL CORE UPDATE STATUS
Failed to get available update data.
There was a problem checking available updates for Drupal

Also, when I try to get a module, I get:
There was a problem checking available updates for your modules or themes.

I'm behind a firewall and I do have to use a proxy.

Even when I use composer to get a module, it stalls at
- Installing relaxedws/couchdb (dev-master 6199e4b): Cloning 6199e4b05b
I'm actually not sure if it's doing anything or just slow installing :(

How do I go about to fixing this issue?

Thank you in advance :)