Be advised, that the RUT955 is supported by "official" openwrt, which is completely open source. Opposed to Teltonikas openwrt variant.
For multiple RUT955, it might make sense to build a custom image, which then can be flashed even to a large fleet of devices.
Remote firmware updates OTA, remote access via VPN, remote configuration possible, of course.
Such work especially makes sense, in case you have a dedicated app, like IoT concentrator, hotspot etc. because "official"openwrt offers newest kernels, newest packages an complete freedom of programming/customization.
For details, please PM.