Trying to install OpenWrt for TD-W8968 V3 on TD-W8968 v5 - "Image uploading failed. The selected file contains an illegal image."

Yes, this is what you must do. Then - you follow the next sentence:

  • WiFi is not enabled by default
  • Also, it's highly unlikely that WiFi works in firmware recovery
  • :warning: You need to use an Ethernet cable - WiFi will not work