Download failed.: cURL error 7: couldn’t connect to host

Hello, when i want to update my wordpress, it is saying:
Download failed.: cURL error 7: couldn’t connect to host

and when i try to add a new plugin, it is now saying:
An unexpected error occurred. Something may be wrong with www.remarpro.com or this server’s configuration. If you continue to have problems, please try the support forums.

It’s the first time this is happening. What is going on, and how can I solve these problems?

The page I need help with: [log in to see the link]