BitDefender's Firewall blocks some of Rapport's functionalities. In order to have the two properly working together, you can either turn the BitDefender Firewall off when installing it, or configure it not to stop Rapport.
Upon installation, you can choose not to turn off Windows Firewall. This will disable BitDefender's firewall and thus it will not interfere with Rapport. You can do this by unchecking the relevant checkbox:
If you choose to install BitDefender's Firewall, you will need to configure it to enable Rapport to access the internet:
1. Open the BitDefender menu by right-clicking the icon in the notification area and selecting "Show"
2. Switch to advanced view by clicking the appropriate button:
3. Go to the Firewall menu on the left, and select the "Rules" tab on the top. Then click the plus sign to add a new rule:
4. Click "Browse" and find your internet browser's execution file (iexplorer.exe or firefox.exe, both usually in their directories under c:\Program files). Select the UDP protocol, and set the action to "Allow":
5. Click OK in all open menus.