Thankfully I was reminded to update my router (Netgear R6250) eventually...
So downloaded and installed the update file.
The router re-booted but the WLAN was gone. Turned out the whole wireless instance was gone and had to be set up again.
But I had a backup file from before the update.
So uploaded this again, the router re-booted and never went beyond "The system is rebooting now. If the restored configuration changed the current LAN IP address, you might need to reconnect manually.":
No LAN, no wireless connectivity, nothing. Hard reset and it kept the update but I cannot get the settings backup onto it- which means a full re-configuration.
What version of OpenWrt were you running previously?
Did you keep settings? If you did not keep settings, this is totally expected.
Depending on the previous version you were running, the backup files may not be compatible.
You may need to reset to defaults. Use failsafe mode so that you can reset to defaults, then you can start configuring from scratch. For most users (i.e. typical configurations), this should take less than 10 minutes.
Well, the previous one was 15.05, r46767.
So there was a bit of a gap in between.
Whether it takes me just 10min we will see. This one is connecting to an ISP device which could not be set in bidge mode but where the Netgear/OpenWRT is just a DHCP client with a static address.
So it seems I need to set up a wireless instance and connect it to the br-lan instance for it to connect to the ISP device- if all goes well.
This way I got my own setup independent from any ISP changes (and I can use OpenWRT...).
Broadly speaking, yes. But it cannot and must not be used directly - only as a human readable reference to help the user remember the gist of the configuration.