The browser extension displays the status of your device by changing colors. It has three states which are displayed by the color.
If the extension can't find Vilfo the logo will be grey. This is typically the case when you're on a laptop and you're on another WiFi network.
However, it can also happen if you just connected to Vilfo for the first time and the device is in the Newly discovered devices column on the Device page. If that's the case - wait up to five minutes before it'll be visible to Vilfo.
It can also happen if you've changed the Settings and edited the IP address for Vilfo.
If your device isn't connected to a VPN tunnel, or if you've decided to bypass a specific website, the logo will be yellow.
Your device is connected to a VPN tunnel and you're protected. Blue is the color you want to have unless you've explicitly decided to bypass a specific website.