To force mark a pfSense gateway as down, you can follow these steps:
- Login to the pfSense web interface.
- Navigate to System -> Routing.
- Find the gateway you want to mark as down in the Gateway column and click the associated gear icon.
- Click the Disable button to mark the gateway as down.
Note: This action is only temporary, as the gateway will automatically be marked as up again once it becomes reachable. To make this change permanent, you will need to adjust the settings in the pfSense web interface.