I think we returned are back to my first question....
As I understand RMS, it is designed to monitor/manage your routers in the field, connected to Internet. But I primary need to connect remotely all device in LAN behing the router, typically PLCs and HMIs. These devices communicate by it's own protocols on it's own ports.So, what it needs is a VPN tunnel, which allows transparent TCP/UTP communication, not only RDP/VNC/SSH/HTTPS protocols. Additionally, with using usual SIM cards or services (no public/static IP, no personal APN), just inserting public SIM card for LTE connection.
So, sorry for my misunderstanding. The only thing not still clear for me is: when I connect RUT955 to Internet via public LTE or WAN, is there a Teltonica's solution how to reach all devices behing RUT955 (for example by VPN connectivity)? Or must I use VPN solution of third party?