The latest firmware of your phone has the maximum size so it will take enough time during download. If you will flash your phone with its latest firmware, your phone will be restored in its original settings, so you will need to take a backup of your data which is on your phone.
You will need to flash your phone with updated firmware, otherwise, your phone will be going to die and you will not able to recover it.
Now you can download the latest firmware of your phone from provided links below. If you are unable to download it from given links, please contact us, we will help you very soon.
Model: Oppo R17 PRO (CPH1877EX)
Firmware Version: Android Pie 9.0
File Size: 2.9GB