You can check around for other threads detailing their adventures using 5Ghz USB dongles, such as this one.

 

 

As for the second issue, typing reboot should issue a soft reboot on the OS, which should “properly” shutdown everything and start it again. I’ve never found this to be necessary though.

If that doesn’t work, I would try re-flashing the firmware.

Maybe your router is not booting into NAND, but NOR instead? The boot medium changing would obviously change the configuration, too.

Have you tried re-flashing the NAND firmware?

You can download the stock NAND firmware for the AR300M on GL-Inet’s firmware pages.

If I recall correctly, you should be able to flash the NAND firmware by booting into the Uboot Web UI and selecting the openwrt-ar300m-nand-2.22.tar file.

You can find details/procedures about entering the UBoot Web UI here.

 

That’s about all I can think of, maybe somebody else has some better insight on this issue.