The new update (14.2610.1711.35) is still based on Android Nougat and the Android Oreo update for ZenFone 4 Pro is expected to release later this month. Besides performance and stability improvements, the update also enables VoLTE and VoWiFi for the CHT (Taiwan) and VoLTE for Softbank networks.  

The new update also includes general bug fixes, improves compatibility of Bluetooth and supports Google Assistant in sleep mode. If you have not received the OTA notification for the update, check it from Settings > About > System Update > and check for update manually. Tech-savvy users can install the update manually by downloading the update file (build 14.2610.1711.35). For example, if you are out of Wi-Fi network area, you may want to install the update manually. Note: If you prefer manual installation and before proceeding with below steps, back up every data you have on the phone. Also, make sure at least 3GB free space remaining on the SD card. Keep in mind that you should download correct firmware build for your SKU. Check the SKU by going to Settings > About > software information > Build number and see the software version for WW, CN, JP, etc. Also Read: Update ZenFone 4 Max to new ZenUI 4.0 version (14.2016.1711.215)

Download and Install 14.2610.1711.35 Update on Asus Zenfone 4 Pro ZS551KL

  1. Download 14.2610.1711.35 update zip file for ZenFone 4 Pro from here [download WW version]
  2. Rename the downloaded firmware file to ‘update.zip’ and save it on your phone.
  3. Boot your phone into recovery mode (Switch off the phone and turn on by pressing Power + Volume Up buttons together).
  4. In recovery, choose Apply update from sd card and then select the update.zip file.
  5. After completing the installation, reboot your phone. (Source)