Thanks, I have regenerated the package adding kmod-usb-serial
However, the problem still occurs.
root@OpenWrt:/# opkg list-installed *usb*
kmod-usb-core - 5.15.167-1
kmod-usb-serial - 5.15.167-1
kmod-usb-xhci-hcd - 5.15.167-1
kmod-usb-xhci-mtk - 5.15.167-1
kmod-usb3 - 5.15.167-1
root@OpenWrt:/# ls -al /dev/sd*
ls: /dev/sd*: No such file or directory
root@OpenWrt:/# dmesg | tail -n5
[ 22.809456] mt7530-mdio mdio-bus:1f wan: configuring for phy/gmii link mode
[ 22.819274] br-wan: port 2(wan) entered blocking state
[ 22.824431] br-wan: port 2(wan) entered disabled state
[ 22.830928] device wan entered promiscuous mode
[ 34.590216] usb 2-1: new SuperSpeed USB device number 2 using xhci-mtk
Have you tried usb 2.0 or usb 3.0 devices?
If you have usb 2.0 devices you should also install kmod-usb2 package.
And what about the power supply? Is it capable of powering HDD or the flash drive along with powering the router?
From your page, I can see I can install these too : kmod-usb-storage-uas kmod-usb3 kmod-fs-ext4 , I will try later. But I don't know why these are not installed by default.