The Online and Arena tabs are greyed out. How do I fix that?

Please make sure you've reached the first breach. If you have, try one of these options:

Check your Internet connection;

• If your Internet connection is fine, restart Steam;
• If that doesn't solve the issue, restart your computer;
• If that doesn't help, try loading this page. If it doesn't load, it means that your Firewall is blocking the connection. Disable your Firewall and try again;
• Try adding the game to your antivirus software exceptions or turning the software off completely. Some software like Kaspersky can prevent the game from connecting to the servers.