Connecting to solar controller (modbus) through RV55

We are testing an EPEVER Tracer AN 10 Amp solar controller ( ) that has Modbus communication through an RJ45 port and we would like to be able to access it remotely through our existing RV55s.

I have an rs232 to rs485 converted that works for connecting the EPEVER to a serial port on a computer (actually a USB to Serial adapter)

I am trying to use Serial/IP to communicate over our VPN through the RV55 to the EPEVER. I use the same system to communicate with our remote equipment and it works fine so I know I am getting to the RV55, just can’t connect to the EPEVER.

Alternately, I would like to be able to communicate with the EPEVER through the usb port on the RV55. I have a USB cable from EPEVER (communicating from PC to EPEVER) and a micro to USB A adapter. I tried setting up port forwarding to the USB port but was not able to communicate that way either.

Any information/ideas/suggestions appreciated.