I have purchased a Teltonika RUT955 router and I have tried to do the same configuration, with a SIM mobile card, but without succes, I can't connect through a VPN connection to the router. I have followed the steps from the above instruction and I also have checked what you suggested, the thing with the protocols security. Can you provide me some support in order to solve this issue? In the "Overview" section, I can see the fact that the SIM card is connected and the ethernet signal is ok. Also, in the "network topology " section, the router is connected to the internet.
Thank you in advance!