There isn't really such a thing as a module that only supports 3G...
Anything could support the minimum needed to connect to an LTE network with the right software update, but modem chipset makers don't make any money rewriting old firmware for old chipsets, so they refuse to rewrite the firmware to support lte.
Anything could support the minimum needed to connect to an LTE network with the right software update, but modem chipset makers don't make any money rewriting old firmware for old chipsets, so they refuse to rewrite the firmware to support lte.