IPFW IPFW Forward RDP packets.

[emmex]

I have a Windows VM with IP address 192.168.0.77.
I use this tcpproxy.conf rule, on a FreeBSD server, for accessing this VM from Internet via Wireguard:

listen * 3390                                                                                            │
{                                                                                                        │
  resolv: ipv4;                                                                                          │
  remote: 192.168.0.77 3389;                                                                             │
};

I want to replace this rule with an IPFW one. I have tried:

ipfw add fwd 192.168.0.77:3389 tcp from any to any 3390

but it doesn't work.
What I am missing ?
Thanks.
--
Maurizio