Just find out, that the zero config / universal NAT feature won’t work when there’s no ip gateway defined on client’s computer
(there is ip address and netmask on client’s but no ip gateway, and no dns ip defined).
Your PC will have to know, where to send data that is not on the local network, gateway. You could make use of DHCP, this way your clients PC is set on auto detect and you give it all the nat, gateway, ip info needed.