I have a RUT240 that I want to configure as a remote VPN server. The SIM card has a public IP which I know, but the router keeps acquiring a private IP. Tech support from the operator told me I need to enter the public IP in the router settings, but I see no way of enabling static IP configuration on the Mobile interface, only on the Wired one. All tutorials and settings just reference the public IP as a done deal, no mention of any settings nor I can find anything in the options. Can you please assist me?