So should I just delete entries in keep.d and sysupgrade.conf, then do a sysupgrade? Or is it just better to upload a new squashfs image? EDIT: Nevermind, you can choose to not keep settings with LuCi.
Hmm, the installation doesn't seem to be without risks. How big of a chance there is to brick the router? Also, since I need to upload this firmware from console and force it, does it make recovering harder? Like does it mess with resetting to factory settings?
Also "clean config -n". Do I need to input this after I flash the firmware? Or before flashing? Do I just input this through SSH in the root?
I'm a beginner so I'm sorry if these questions sound stupid.
There will be always a small risk to soft brick your device, but if you have a complete backup of you flash you could always recover your device.
Take a look in the openwrt wiki page for your wndr3700, there is the tftp recovery mentioned if something went wron in your flashing process...
Take a look at here how you can backup all your partitions of your flash.
The command to install is mentioned below this text.
sysupgrade -n -F /tmp/xxx.img
The -F does force the upgrade because the device name of ath79 doesn´t match with the one in the ar71xx target.
The -n does not backup any configuration and you does start with a clean config set. Do a manual backup with sysupgrade -b or with luci if you want.