How to best present minimum requirements for device use for web application?

Currently, I do have to work with a legacy web application that can be hard to use via certain mobile devices of older generations due to performance issues. There is already a "Minimum Requirements" paragraph in the FAQ for desktop in place on the website, similar to descriptions on the back of game packages.

Now, I was wondering how such a paragraph could look like regarding the many issues that the web applications has on mobile. Do you have any recommendations on how to address the limitations of the web application regarding a certain range of mobile devices? I'd like to adjust people's expectations, so there'll be maybe fewer complaints about the application. (Unfortunately, to fix all the problems is no option!)

The problems occured after the web application was transitioned from Flash to HTML5. There are many animations and sound effects involved.