I did recently an updated (sudo apt-get updated && sudo apt-get dist-upgrade) on my 3 raspberies.
Two RPI 3B, and one RPI Zero W.
The strange thing is that the raspberries that I installed later (a year later), have the newest kernel and bootloader, deb package version
But my oldest Raspberry (3B) is stuck with
sources.list on all of them is the same:
deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
Should I change some option in config.txt or something to get newer kernel? Both RPI 3B are version 1.2.