R6300 User Manual (PDF)
Page 72
... the router after upgrading. The upgrade process typically takes about 1 minute. R6300 WiFi Router 802.11ac Dual Band Gigabit Upgrade the Router Firmware The router firmware (routing software) is stored in .img). Click Yes to update and locate the firmware you need to determine whether or not you downloaded (the file ends in flash memory.
... the router after upgrading. The upgrade process typically takes about 1 minute. R6300 WiFi Router 802.11ac Dual Band Gigabit Upgrade the Router Firmware The router firmware (routing software) is stored in .img). Click Yes to update and locate the firmware you need to determine whether or not you downloaded (the file ends in flash memory.