Hello,
Based on the description and my understanding I am providing the general idea about the solution.
However, if you can provide me more details about the solution:
1. If possible can you share me the Topology? and
2. Which devices are you trying to access in RUT240's LAN?
3. Are you using or going to use the Public IP or not?
Correct me if I am wrong. From the description, You want to connect two RUT240 that are remotely located from each other and access devices of one RUT240's LAN from another RUT240.
There are multiple ways we can do this.
1. VPN: You can use the VPN service for the Devices(OpenVPN, GRE, L2TP and more).
If you are going to use the VPN you will need at least 1 public IP on any one of the Router.
If you don't want to get the Public IP, you can use third party services like NordVPN, Expressvpn and more.
Also for easy accessibility, management and less configuration you can use RMS VPN.
2. RMS VPN: if you want to use the RMS VPN it can help with easy configuration and has
an inbuilt options to reach the devices in the LAN of both router.
For more details on VPN follow link:
https://wiki.teltonika-networks.com/view/RUT240_Configuration_Examples#Use_cases
For more details on RMS VPN Follow link:
https://wiki.teltonika-networks.com/view/VPN_Hubs