Just wanted to make my new script (weekend's work ;-)) available to the community.
It checks if extroot is mounted and tries to fix common problems (UUID, e2fsck, changed hardware etc.) I built this for my TP-Link Archer C7's because I wanted to have 1 out of my 3 routers to be cold standby for the other 2 and automatically play the role of router 1 or router 2 depending on the USB stick that is plugged in.
In the current version you need rsync to make file sync work - tar piping was not an option as the two routers are too different and I might have ended up with mixed configs.
Comments are in German, sorry - but Google translate is your friend. Script can be accessed on github