I followed these instructions to flash OpenWRT on D-LINK DCH-G020 https://openwrt.org/toh/d-link/d-link_dch-g020_a1 with one exception, I expanded my storage via an external USB3 disk - SanDisk Ultra Fit 32GB USB 3.0 Flash Drive.
Everything went smoothly after I struggled getting the USB disk recognised initially and later while adding Z-Wave devices, one device hanged and I had to cold reboot the DCH-G020 which was a bad idea.
Now I boot without the extra disk space, no other ext4 USB drives are recognized USB2 nor USB3, I can open the USB disk normally on other .nix systems and it didn't need any repair, additionally I can see the /dev/sda1 mount point on LUCI as not present.
dmesg, kernel and system logs don't seem to be helpful and the following is the output of block info; uci show fstab; logread | sed -n -e "/- preinit -/,/- init -/p"
/dev/mtdblock7: UUID="3635b929-78bbf660-7a2e4134-481e92d7" VERSION="4.0" MOUNT="/rom" TYPE="squashfs"
/dev/mtdblock8: MOUNT="/overlay" TYPE="jffs2"
fstab.@global[0]=global
fstab.@global[0].anon_swap='0'
fstab.@global[0].anon_mount='0'
fstab.@global[0].auto_swap='1'
fstab.@global[0].auto_mount='1'
fstab.@global[0].delay_root='5'
fstab.@global[0].check_fs='0'
fstab.@mount[0]=mount
fstab.@mount[0].target='/mnt/sda1'
fstab.@mount[0].uuid='36ca38ac-af32-46ed-826b-bf21ce8d115a'
fstab.@mount[0].enabled='0'
fstab.rwm=mount
fstab.rwm.device='/dev/mtdblock8'
fstab.rwm.target='/rwm'
fstab.rwm.enabled='0'
fstab.overlay=mount
fstab.overlay.uuid='d20ff3b4-74d3-496e-b361-c12a290162ba'
fstab.overlay.target='/overlay'
fstab.overlay.enabled='0'
Tue Jul 5 23:55:43 2022 user.info kernel: [ 3.346286] init: - preinit -
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 4.613056] random: jshn: uninitialized urandom read (4 bytes read)
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 4.908660] random: jshn: uninitialized urandom read (4 bytes read)
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 5.094778] random: jshn: uninitialized urandom read (4 bytes read)
Tue Jul 5 23:55:43 2022 kern.info kernel: [ 5.790650] eth0: link up (1000Mbps/Full duplex)
Tue Jul 5 23:55:43 2022 kern.info kernel: [ 5.800014] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
Tue Jul 5 23:55:43 2022 kern.info kernel: [ 5.815916] IPv6: ADDRCONF(NETDEV_CHANGE): eth0.1: link becomes ready
Tue Jul 5 23:55:43 2022 kern.warn kernel: [ 5.859109] urandom_read: 4 callbacks suppressed
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 5.859120] random: procd: uninitialized urandom read (4 bytes read)
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 10.114083] jffs2: notice: (599) jffs2_build_xattr_subsystem: complete building xattr subsystem, 38 of xdatum (29 unchecked, 9 orphan) and 49 of xref (9 dead, 0 orphan) found.
Tue Jul 5 23:55:43 2022 user.info kernel: [ 10.138316] mount_root: loading kmods from internal overlay
Tue Jul 5 23:55:43 2022 user.info kernel: [ 10.421745] kmodloader: loading kernel modules from /tmp/overlay/upper/etc/modules-boot.d/*
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 10.854384] SCSI subsystem initialized
Tue Jul 5 23:55:43 2022 kern.info kernel: [ 10.979331] usbcore: registered new interface driver usb-storage
Tue Jul 5 23:55:43 2022 kern.info kernel: [ 10.992859] usbcore: registered new interface driver uas
Tue Jul 5 23:55:43 2022 user.info kernel: [ 10.999667] kmodloader: done loading kernel modules from /tmp/overlay/upper/etc/modules-boot.d/*
Tue Jul 5 23:55:43 2022 user.info kernel: [ 11.221385] block: attempting to load /tmp/jffs_cfg/upper/etc/config/fstab
Tue Jul 5 23:55:43 2022 user.info kernel: [ 11.232099] block: extroot: not configured
Tue Jul 5 23:55:43 2022 user.info kernel: [ 11.237809] mount_root: switching to jffs2 overlay
Tue Jul 5 23:55:43 2022 kern.warn kernel: [ 11.270147] overlayfs: upper fs does not support tmpfile.
Tue Jul 5 23:55:43 2022 user.warn kernel: [ 11.281561] urandom-seed: Seeding with /etc/urandom.seed
Tue Jul 5 23:55:43 2022 kern.info kernel: [ 11.389656] eth0: link down
Tue Jul 5 23:55:43 2022 user.info kernel: [ 11.424187] procd: - early -
Tue Jul 5 23:55:43 2022 user.info kernel: [ 11.427311] procd: - watchdog -
Tue Jul 5 23:55:43 2022 user.info kernel: [ 12.070426] procd: - watchdog -
Tue Jul 5 23:55:43 2022 user.info kernel: [ 12.076856] procd: - ubus -
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 12.171861] random: ubusd: uninitialized urandom read (4 bytes read)
Tue Jul 5 23:55:43 2022 kern.notice kernel: [ 12.182067] random: ubusd: uninitialized urandom read (4 bytes read)
Tue Jul 5 23:55:43 2022 user.info kernel: [ 12.199458] procd: - init -
Any pointers will be appreciated, thanks for taking the time to read my message.