a lot of platforms, but it works really well for me. The screenshots i made are in german, but it should be similar in any other language.
1. download the ifttt app for your iOS device from the appstore.
2. register an choose the following applet:
you have to configure your dropbox account in ifttt-app if you use it the first time.
At this state all of your newly taken iOS photos will be uploaded to your dropbox. you can also put your pictures to your google drive.
3. download your pictures from dropbox or google drive to your QNAP
you have to install the cloud drive sync app for your QNAP
than configure your account (dropbox or google-drive)
4. now create a sync job from your cloud account to a local folder of your NAS-Storage.
Thats it! have fun!