You mentioned a web server. What type of app is this? Web App? If so:
- What version of the runtime are you targeting with it? Is your app MVC, Angular, what?
- Can you clarify what isn't rendering properly? For example the images that don't load are static images in the content folder, images that are backed by an ASPx handler, generated from a controller, etc?
- What does the browser show in these cases? The network tab will show you requests for the images and the results. Is the browser getting the image, getting garbage, getting partial, etc.
- Do the images have any caching enabled? Do you have static or dynamic compression enabled on IIS?
- Is this impacting all browsers or only some (and which one's)?