If your computer is in a subnet that uses NAT

If your computer resides in a subnet that uses NAT (Network Address Translation), all computers in the subnet share the same external IP address, while the individual computers in the subnet have internal IP addresses.

In this case, you must set up a port mapping from the external ports 6991 and 6992 to your internal ports 6991 and 6992, that is, the actual ports on your computer, as opposed to the ports of the subnet.