Issue establishing Modbus TCP connection over LX40 gateways

I am attempting to link 2 PLCs running on a VPN over the T-Mobile network using LX40 gateways. I can successfully ping each gateway from the other’s AceManager ping tool so I have confirmed connectivity. I need to establish a modbus session over port 500 on the slave (remote) PLC feeding into the master PLC. I have my port forwarding set up on the slave side. I can get this configuration working if I replace the LX40 in front of the master with a Cradlepoint IBR-200 unit. This implies that it has to be something in the configuration of the master gateway. Can anyone assist with suggested configuration options for what to try?

Hi Matt.Pickney,

First, please make sure you are running the latest FW.

If you cannot succeed in the latest FW, please share your network topology; and your MODBUS and PAD tab in ACEmanager for both host and remote side. You could message me this kind of info.