Where ``{public_ipv[46]}`` is the public IP of your server, or at least the LAN IP to where your NAT will forward to, and ``{listening_ipv[46]}`` is the private ipv4 (like 10.0.34.123) that the instance is using and sending as connection parameter.
Additionally in order to access the server by itself such entries are needed in ``OUTPUT`` chain (as the internal packets won't appear in the ``PREROUTING`` chain)::