Photos look sharp in the blog post editor but blurry after being published.

Hi in my website I formatted all my photos to have a maximum width of 1000 px. All the horizontal photos look sharp and crisp while the vertical photos always looks blurry. The thing is, all those photos look nice and sharp in the blog post editor including the vertical ones. Any idea how to fix this?

Example of my blog post: Belitung 2016 – Day 4 – Cichill

Currently here’s my Wordpress media settings:
Thumbnail size: Max Width 300 px. Max Height 300 px
Medium size: Max Width 300 px. Max Height 300 px
Large size: Max Width 1024 px. Max Height 1024 px.

Every time I uploaded a photo I will choose to show its original size on the blog post editor. Please help. Thank you!

Regards.

Hello there,

I hope you are doing well today.

Please try using the following plugin to regenerate your thumbnails and images:

Best Regards,
Support

Hi guys all plugins about regenerating thumbnails did not work. Are there any other things I can try? Thanks so much, appreciate it a lot.