New unboxed Cisco ISR4331, command configure terminal didn’t work. Looks like the router is booted in controller mode by default. To get back to “legacy” mode you need to disable controller mode.
Router#conf t This command is not supported
Router# controller-mode disable Disabling controller mode will erase the nvram filesystem, remove all configuration files, and reload the box! Ensure the BOOT variable points to a valid image Continue? [confirm] % Warning: Bootstrap config file needed for Day-0 boot is missing Do you want to abort? (yes/[no]): no Mode change success
Wait a few minutes, router will reload.
Router>en Router#conf t Enter configuration commands, one per line. End with CNTL/Z. Router(config)#