By default, pings are not allowed and actually not recommended. Bu during a network debugging, it can be quite handy.
In order to allow ping incoming on the pfSense WAN port, go to Firewall >> Rules >> WAN page and create a new rule by clicking on Add button (down arrow icon) and do as follows:
- Action: Pass
- Protocol: ICMP
- ICMP subtypes: Echo request
- Source: any
- Destination: This Firewall
- Description: Allow ping on WAN
At the end, click on Save and Apply changes.