I am at a loss on the connection test

[Zacchaeus]

i Have little knowledge of such set ups but you could try routing it to 192.168.1.1

[Moon Wizard]

You have to chain the port forwarding when there are multiple routers.

On 192.168.1.1 device, you forward port 1802 to the local IP address reported by Fantasy Grounds.
On 192.168.0.1 device, you forward port 1802 to the external/WAN IP address reported by the first router (192.168.0.#)

Cheers,
JPG