How to fix it...
Network Connection Error [Code: 10000005]. Connection errors are typically caused by a temporary server outage, a firewall, or a problem with your internet connection. If it's been a long time since you've connected to Voobly it's recommended that you redownload the client from the website.

This is a temporary network connection error. Try to connect again after a while and you should be fine.

P.S: Do make sure that you have a stable and consistent internet connection. If the problem persists, tell us how you connect to the internet (in detail).