If you are using ShortPixel Image Optimizer (SPIO) and Cloudflare, and you encounter 503 errors when trying to optimize an image, it is possible that all you need to do is whitelist our IPs in Cloudflare’s control panel.
You can confirm this by opening your image URLs in an Incognito/Private window. If you see the following, it means you have DDoS protection enabled in Cloudflare, which is preventing ShortPixel’s servers from accessing the images for optimization.
To learn more about how to properly configure Cloudflare to work with SPIO, click here.