I've got a PLC that has a static IP I can't change and a gateway that can't be set. I need to be able to talk to the PLC over TCP on my corp network. Seems like a good candidate for NAT...
I've added a TC-Link ER605 router in front of the PLC with a network matching the network for the PLC (192.168.1.1/24) and I've got the WAN configured to a subnet on my network (10.15.70.19/24). I've created a NAT rule (virtual Server) shown below.
When I try to connect to the PLC from the WAN side (10.15.70.19:502), it times out.
When I'm plugged into the LAN side I can open a connection to 192.168.1.88:502 no problem.
I think the problem is that the packets can get to the PLC, but the PLC doesn't have a gateway and doesn't know where to send the packets back. I've confirmed this by substituting a laptop for the PLC and running Wireshark. I'm not sure what else to try here.
Any help or insight into my assumptions would be appreciated.