You must be absolutely sure that your USB cable supports the data connections. Many cheap cables do not, and can be used for charging only.
Thus I mark all my USB cables which support data with "data" on them.
Your other options is to go and buy a USB cable that is made specifically for data and make sure that works before looking for other problems. Don'...
It's difficult to answer this in a format that's useful for Stack Exchange since it usually turns into a long comment thread of "Have you tried this?" so I'll try a more generic answer.
The sequence I follow when trying to debug things like these is to systematically swap out things to see what could affect it. You have already swapped the operating system ...
Assuming the book(s) have no DRM, this is what I do:
Connect your phone to your computer and move the epub onto your
Import the epub into Calibre.
Connect your Kobo to your computer.
Use Calibre to load the epub onto your Kobo.