This could be due to to numerous factors:

  1. Upload speed is slow: To test your upload speed, please go to:
  2. Your WiFi is set to turn off during sleep: To change this setting, please refer to the following article:‎
  3. Too much internet activity: Try to run backups when there is minimal internet activity, it is recommended to keep the first backup to run overnight and plugged in.
  4. Some ads blocking apps might slow down G Cloud and affect the upload process, so try to disable them temporarily to see if this speed up the upload.