importing same images over and over + cannot complete the import

Hello,

There is a list of problems.

1. As you can see in the image, it’s importing the same image over and over even after product import is finished.
2. When importing products, blog posts always stops in the middle and get 504 gateway timeout error. When I check the result it imports some of the posts and not all.
3. Also, I was never able to import everything because somehow it stops on the way. On the progress bar, usually on product categories or coupons, it says importing but it just does progress from there no matter how long I wait for it to be completed.