Oh uninstall the add-on will disable r2. Got it. Images are back.
In that server, I don't need R2 for now. It serves me for other purpose. Will play with R2 later for other cases.
As for the new server, R2 is serving without problems. Pictures are showing lazy load like (each picture appears from top part to full in a fraction of second, all pictures load at the same time in this way). It's this normal?
But The other server which I just disabled (uninstalled the add-on) R2, pictures load instantly.
I didn't really do anything for lazy load settings.