AR46 version is VRP340-R0109. After upgrade the version is VRP340-R0109P17.
1. Version upgrade guide describes FTP upgrade needs much setting in Ethernet sub-menu. It is different from other router and switch.
2. Enable FTP server on AR46 and configure FTP account. Load the version to flash and compare the size of upgrade source file and loaded file. AR46 ahs no startup or boot command to designate started program file as next started file. Reboot the device and ctrl+b to MAIN-BOOTROM MENU, choose <5> Boot File Control and <1> Display Available Boot File. For two displayed files, one is loaded upgrade version and another is attached version of the device. Choose <2> Set Main Boot File. When it indicates Input main boot file name->input upgrade version filename ar46-vrp340-r0109p17.bin. Return and restart the device. The upgrade is normal.