There are many reasons that a registry may be offline. In most cases, a registry is offline for maintenance purposes.
To immediately find out if a registry is currently offline, you can use this link: Registry status page
You will be offered the option to subscribe to the registry offline notifications on this page.
On this page, you will see the status of the API and the portal alongside the scheduled maintenance and outages of the registries:
Click on the + symbol beside each country name to see the status of its registry.
This will maximise the view for the selected country.
To minimise the view, simply click on the - symbol.