i created a network environment on virtualbox of many vms and one being a firewall. I set the gateway to be the ip of the firewall and have traffic come in and out through opnsense. I am able to ping devices on LAN and the firewall and i can ping DNS but i can't seem to be able to ping servers. i cannot ping you youtube or google.
Through Opnsense GUI, there are no rules other than the auto generated ones for LAN and WAN.
https://www.virtualbox.org/manual/topics/networkingdetails.html#networkingdetails please first indentify the type of networking set on/for your VMs before checkinbg that your OPN setup is correct.