Due to my previous OpenWrt router having become a bit outdated, I got myself a shiny new Linksys MR8300 V1.1, which I am in general quite happy with.
I opted directly for the lastest available release candidate, OpenWrt 22.03.0-rc4, and it's up and running.
There is just one annoying issue with the USB port.
I'd like to use the MR8300 as a router with built-in NAS functionality, by installing Samba server on it and plugging a flash drive (thumb drive) into its USB port.
However, when running OpenWrt the router won't register any of my flash drives.
I have tried four different flash drives covering the whole range from superfast Sandisk USB3 to cheap no-name USB2.
Fearing the worst I switched back to the Linksys software on the other partition and all four drives work absolutely perfect there.
Back to OpenWrt I started experimenting with a USB 3.0 switch. Here is what I've found.
- USB flash drive plugged directly into MR8300's USB port -> none of 4 drives work
- USB switch plugged into MR8300's USB port and USB flash drive plugged into switch -> none of 4 drives work
- USB switch plugged into MR8300's USB port, USB flash drive plugged into switch and external 5V power supply connected to the USB switch -> all 4 drives work flawlessly
I further noticed that once the USB flash drives are registered by OpenWrt I can unplug the external power supply from the USB switch and everything still keeps working fine. (that is, until I power cycle or reboot the MR8300)
To troubleshoot this anomaly I plugged an adjustable load into the MR8300's USB port to test if there may be a issue with the USB port not supplying sufficient power. I turned the current up to 500 mA (0,5 A), which the USB port successfully managed to supply.
Next I used a so-called "USB Safety Tester" that can be plugged in between an USB port and an USB device to measure how much current my USB flash drives draw. They were all within a range of 20 mA to 60 mA, which obviously is just a tiny fraction of the power the USB port is capable of supplying.
However, during that test I noticed that the USB tester would restart right after I've plugged a flash drive into the USB tester's USB port. That "USB tester" doesn't read any bus signals, it just hooks itself up to the 5VDC USB power rail to measure voltage and current and itself operates of the USB port's power. If it restarts it can only mean that power was interrupted for a very short moment.
So it kind of appears to me as if OpenWrt was cutting the USB power for maybe a few milliseconds right at the moment the USB drive negotiates the connection with the router's USB port.
Plugging a powered USB switch in between the router's USB port and the USB drive basically helps to bridge that power interruption.
Has anyone else experienced such issues with the MR8300's USB port when using OpenWrt?
In case someone else here has the same router, but no problems with the detection of USB thumb drives, then can you please let me know which version of OpenWrt you are using or if you maybe have installed a special driver package or whatever?
So far the workaround with the powered USB switch has been working stable, but I would like to get rid of the powered switch, if possible.