17.01.4 on Netgear WNR2000v1 doesn't save config

Built 17.01.6 with LuCI and without ipv6 today.
It appears working fine:

BusyBox v1.25.1 () built-in shell (ash)

     _________
    /        /\      _    ___ ___  ___
   /  LE    /  \    | |  | __|   \| __|
  /    DE  /    \   | |__| _|| |) | _|
 /________/  LE  \  |____|___|___/|___|                      lede-project.org
 \        \   DE /
  \    LE  \    /  -----------------------------------------------------------
   \  DE    \  /    Reboot (17.01.6, r3979-2252731af4)
    \________\/    -----------------------------------------------------------

root@LEDE:/# c[   79.873398] random: nonblocking pool is initialized

root@LEDE:/# cat /proc/mtd
dev:    size   erasesize  name
mtd0: 00040000 00010000 "u-boot"
mtd1: 00010000 00010000 "u-boot-env"
mtd2: 003a0000 00010000 "firmware"
mtd3: 00270000 00010000 "rootfs"
mtd4: 00050000 00010000 "rootfs_data"
mtd5: 0012da48 00010000 "kernel"
mtd6: 00010000 00010000 "art"
root@LEDE:/# df -k
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/root                 2304      2304         0 100% /rom
tmpfs                    14100       316     13784   2% /tmp
/dev/mtdblock4             320       216       104  68% /overlay
overlayfs:/overlay         320       216       104  68% /
tmpfs                      512         0       512   0% /dev
root@LEDE:/#

Load uImage.bin to 0x2c0000, and update bootm accordingly (setenv bootcmd "bootm 0xbf2c0000").

Boot logs:

[    0.775628] m25p80 spi0.0: found mx25l3205d, expected m25p80
[    0.781434] m25p80 spi0.0: mx25l3205d (4096 Kbytes)
[    0.786366] 4 cmdlinepart partitions found on MTD device spi0.0
[    0.792338] Creating 4 MTD partitions on "spi0.0":
[    0.797168] 0x000000000000-0x000000040000 : "u-boot"
[    0.805091] 0x000000040000-0x000000050000 : "u-boot-env"
[    0.812723] 0x000000050000-0x0000003f0000 : "firmware"
[    0.826507] 2 uimage-fw partitions found on MTD device firmware
[    0.832541] 0x000000050000-0x0000002c0000 : "rootfs"
[    0.839547] mtd: device 3 (rootfs) set to be root filesystem
[    0.845283] 1 squashfs-split partitions found on MTD device rootfs
[    0.851532] 0x000000270000-0x0000002c0000 : "rootfs_data"
[    0.859116] 0x0000002c0000-0x0000003eda48 : "kernel"
[    0.866353] 0x0000003f0000-0x000000400000 : "art"

[    8.010259] jffs2: notice: (327) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
[    8.027635] mount_root: switching to jffs2 overlay




18.06.1 (w/o ipv6) appears working, also:


BusyBox v1.28.3 () built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 OpenWrt 18.06.1, r7258-5eb055306f
 -----------------------------------------------------
root@OpenWrt:/# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/root                 2304      2304         0 100% /rom
tmpfs                    14192        48     14144   0% /tmp
/dev/mtdblock4             320       232        88  73% /overlay
overlayfs:/overlay         320       232        88  73% /
tmpfs                      512         0       512   0% /dev
root@OpenWrt:/#