What is the audio player that does not work? Is CD-R support mentioned in the specs?
Can it sometimes read the discs and sometimes lose the track? Or does it not load the discs at all? Do you have old burned discs that still always work with the same player device?
The writable discs have less reflectivity than factory made standard audio CDs. An older player device may not have been manufactured to specifically support the less reflective burned discs. A player may have been able to (barely) read such discs when it was new, but not anymore. Also different brands of disc media may have differences in reflectivity even in the same category (CD-R or CD-RW). In addition the burners do not get better over time. A DVD player is is usually designed to be able to read writable media and is likely to have more tolerance for less than ideal burn quality and reflectivity.
Sometimes cleaning the laser lens helps.
You could try the following strings in Google searches:
- audio CD compatibility CD-R CD-RW reflectivity
- CD drive laser lens dust wear aging