Hi,
kindly note that you cannot upload the config file to a device that has different product code via WebUI.
The config file can be uploaded it to another device has the same FW (or newer) and the same product code.
But you can do it via copy/past the config files from the config file from your pc to the router (on /etc/config directory) by using Winscp app for example, then reboot the device.
Thanks