Run sysupgrade or upload the new file with LuCI.
opkg update opkg install block-mount opkg install kmod-fs-ext4 opkg install kmod-usb-storage mount /dev/sda1 /mnt rm /mnt/etc/.extroot-uuid reboot
block detect > /etc/config/fstab;
sed -i s/option$'\t'enabled$'\t''0'/option$'\t'enabled$'\t''1'/ /etc/config/fstab;
sed -i s#/mnt/sda1#/overlay# /etc/config/fstab;
cat /etc/config/fstab;
opkg upgrade $(opkg list-upgradable | awk '($1 !~ "^kmod|Multiple") {print $1}')