USB device dropped by OpenWrt (WRT1900ACS, USB device disappears after a while)

I followed USB quick install guide to use external USB with my LinksysWRT1900ACS.
After couple of days of use, the USB drive is no longer seen / operational by OpenWrt. This has been observed for both USB 2.0 and USB 3.0. I have AGH installed on this USB drive - each time USB drive is "lost" for OpenWrt, this brings all of the network down (no DNS service available).
What can I do to fix this USB issue?

Is this a pendrive or some disk? The latter may disappear due to lack of power from the router if it is not powered externally from its own power supply. The first may wear out from reads/writes.

This is new pendrive. Could be faulty. But my first thought was about OpenWrt settings.

Can you explain how “AGH installed on this USB drive”?
Do you see your drive in block info?
Can you still access the drive when this happens?

I’m inclined to think there is something amiss in the setup of AGH given the type of issue you report.

I mounted USB as /opt (not the original /mnt/sda1) by manually changing fstab. fstab now looks like this:

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

config mount
	option target '/opt'
	option uuid '____________________'
	option enabled '1'

I set up AGH as suggested by mercygroundabyss here: [How-To-Updated 2021] Installing AdGuardHome on OpenWrt [Manual and opkg method], using the install script to install AGH to /opt.

block detect on the other hand now looks different from 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    '_____________________'
        option  enabled '0'

Probably this is where the possible reason lies. I am afraid I do not understand how come fstab and results from block detect are different and how they became different, and how to make so that fstab settings are not overridden in the future.