trouble with nat in debian 10

I have a Debian firewall running nat. I can connect to the internet from the firewall and can hit the outside network from a windows pc connected to the second (internal) interface of the firewall. The problem is, when I try to use a Linux computer (I have a pc and a laptop both running Debian)I can only ping the address of the inside card of the firewall but not anything past it. Traceroute will fail before it even gets to the firewall.