RPC Error trying to use 2 external usb storage

Installing and Using OpenWrt
1

I've added 2 external usb devices to the TP-Link Archer C7 (v2) router-wifi. The /sdb1 is an extended partition or added external storage. It was added after /sda1, which holds the media for minidlna.

root@OpenWrt:/etc/config# cat fstab

config global
	option anon_swap '0'
	option anon_mount '0'
	option auto_swap '1'
	option auto_mount '1'
	option delay_root '5'
	option check_fs '0'

config mount
	option target /mnt/sda1
	option uuid e8577c39-a69c-4a4e-8717-26de715249ec
	option enabled 1

UUID=e8577c39-a69c-4a4e-8717-26de715249ec       /mnt/sda1       ext4    default>

UUID=79792aac-afdb-48b6-9ac4-25062f5f3715       /mnt/sdb1       ext4    defaults

config mount
        option  target  /overlay
        option  uuid    79792aac-afdb-48b6-9ac4-25062f5f3715
        option  enabled 1

Do I need to switch locations on the external usb devices? Make /sdb1 into sda1?

root@OpenWrt:/etc/config# df -h
Filesystem                Size      Used Available Use% Mounted on
/dev/root                 3.5M      3.5M         0 100% /rom
tmpfs                    60.3M      3.4M     56.8M   6% /tmp
/dev/sdb1                 3.5G     61.0M      3.3G   2% /overlay
overlayfs:/overlay        3.5G     61.0M      3.3G   2% /
tmpfs                   512.0K         0    512.0K   0% /dev

root@OpenWrt:~# mount /dev/sdb1 /mnt
root@OpenWrt:~# cp -a /overlay/. /mnt
cp: '/overlay/.' and '/mnt/.' are the same file


root@OpenWrt:~# block info | grep "/dev/sd"
/dev/sda1: UUID="e8577c39-a69c-4a4e-8717-26de715249ec" LABEL="OpenWRT500" VERSION="1.0" TYPE="ext4"
/dev/sdb1: UUID="79792aac-afdb-48b6-9ac4-25062f5f3715" VERSION="1.0" MOUNT="/overlay" TYPE="ext4"

I'm still researching and found this but I don't see a problem.

root@OpenWrt:~# ubus call luci-rpc getHostHints
{
	"00:01:5C:6E:56:46": {
		"ipaddrs": [
			"104.35.224.1"
		],
		"ip6addrs": [
			"fe80::201:5cff:fe6e:5646"
		],
		"name": "cpe-104-35-224-1.socal.res.rr.com"
	},
	"00:18:DD:04:90:04": {
		"ipaddrs": [
			"192.168.1.229"
		],
		"ip6addrs": [
			
		],
		"name": "HDHR-10490046.lan"
	},
	"0C:FE:45:6B:6D:5C": {
		"ipaddrs": [
			"192.168.1.151"
		],
		"ip6addrs": [
			"2603:8000:d300:cad::c07",
			"fdbc:9f2e:948::c07",
			"fe80::efe:45ff:fe6b:6d5c"
		],
		"name": "2603-8000-d300-0cad-0000-0000-0000-0c07.res6.spectrum.com"
	},
	"18:30:0C:22:BE:01": {
		"ipaddrs": [
			"192.168.1.103"
		],
		"ip6addrs": [
			"2603:8000:d300:cad:4545:8618:cd85:ca0c",
			"2603:8000:d300:cad:7d1e:4de8:3de7:2ef5",
			"2603:8000:d300:cad:f9b7:7a6a:11b0:daa5",
			"fdbc:9f2e:948:0:4545:8618:cd85:ca0c",
			"fdbc:9f2e:948:0:6516:455:e737:640b",
			"fdbc:9f2e:948:0:7d1e:4de8:3de7:2ef5",
			"fdbc:9f2e:948:0:95ce:cb9:c6aa:936b",
			"fdbc:9f2e:948:0:f9b7:7a6a:11b0:daa5",
			"fe80::4564:8a13:bcb8:d7c3"
		],
		"name": "2603-8000-d300-0cad-f9b7-7a6a-11b0-daa5.res6.spectrum.com"
	},
	"18:D6:C7:24:82:B4": {
		"ipaddrs": [
			
		],
		"ip6addrs": [
			"fe80::1ad6:c7ff:fe24:82b4"
		]
	},
	"18:D6:C7:24:82:B5": {
		"ipaddrs": [
			"192.168.1.1"
		],
		"ip6addrs": [
			"fe80::1ad6:c7ff:fe24:82b5"
		],
		"name": "OpenWrt.lan"
	},
	"18:D6:C7:24:82:B6": {
		"ipaddrs": [
			"104.35.246.9"
		],
3

Researching:

Network and RPC errors after snapshot install #4610

The poster says: 

I think I found the problem, the default uhttpd config file has this option commented out:
`# option ubus_prefix '/ubus'`
If I uncomment it and restart uhttpd, I don't see any errors anymore.

I don't see what directory that file is in that has a line than need "commenting". I found a file named: ubus (in green color). I don't know if that is the correct object. Also, that file cannot be read with the cat command; only gibberish comes onscreen. Can someone point me the right direction?