My guide to avoiding rotated images on upload:
You could just take photos with the phone pointed landscape normal (home button on right on iPhone). These images will always upload correctly.
But for any problem images that do not upload correctly, or you are not sure and want to just run them through a process to be sure to be sure:
(1) Install NConvert . Download from
https://www.xnview.com/en/nconvert/ for your platform (Windows/Mac/Linux). This is a command line utility. If you are comfortable with the command line interface, run the command .
"nconvert -overwrite -jpegtrans exif *.jpg"
This will overwrite all jpeg images that you have put in the same directory as the ncoverter.exe with the correct orientation based on its EXIF orientation tag.
or
(2) If not comfortable with the command line interface, install XnConvert, which is a GUI for NConvert. Download from here
https://www.xnview.com/en/xnconvert/ for your platform.
Under input tab, load all your image files
Under 'Settings' tab, make sure that
'Rotate images according to EXIF orientation tag' is selected . Hit convert. The default setting is that new images are created with the '_result.jpg' appended to the file name.
Either of these two methods will transform the image data so that it displays correctly.
A final word. Any pix that have been edited or exported from a 'photo album' or viewer type software, may well upload correctly without you having to do anything. There are lots of variables here such as your image software doing a physical rotation for you without you being aware. Either way, you can still run them through NConvert.