Is there a module or technique to display blocks or panels based on device width? We have our ads set up as blocks or panels and we would like to prevent wide ads from rendering on narrow (mobile) devices. Additionally, we would like to render other ads only on wide (desktop) devices.

I'm new to drupal and new to the website in question, and I'm having trouble finding where the actual ad calls are made, so I figured the best solution would be to handle this at the block/panel level. 

To be clear, I am trying to prevent the ads from even rendering, not just trying to hide them from view once rendered.
How about using the Themekey and/or Mobile Detect for switching mobile and desktop version of themes? Here is a quote about these modules (from their project pages):

Themekey:


ThemeKey allows you to define simple or sophisticated theme-switching rules which allow automatic selection of a theme depending on current path, taxonomy terms, language, node-type, and many, many other properties. It can also be easily extended to support additional properties exposed by other modules.
... in combination with Drupal's theme inheritance you can easily achieve features like ... &quot;mobile themes for different auto-detected mobile devices&quot;.


Mobile Detect:


... intended to aid developers utilizing mobile-first and responsive design techniques who also have a need for slight changes for mobile and tablet users. An example would be showing (or hiding) a block or content pane to a particular device.