A solution could be setting your IP-Settings the right way. If these 2 networks communicate with each other they should be connected by a router or a Layer 3 switch. If this is the case you should set the Gateway/Address from your router in the HW-Config. In that case both CPU's can reach each other. Then you need to make sure that port 102 isn't bloked by a firewall in the Router/L3-Switch and it should work.

If both device are connected by a standard switch e.g. not a router then there is no other solution then using the PN/PN Coupler.