Hello tonyfpz,
Thanks for that info and choosing the Apple Support Communities. I know how important being able to use your Beats headphones with your iPhone 7 is to you! The good news is the following steps will be helpful in resolving your issue with the Lightning to 3.5 mm Headphone Jack Adapter and get you back to enjoying your new iPhone 7!
1. Make sure your iPhone is up to date, as the updates contain stability fixes that can resolve issues like yours, as well as important security updates to keep your iPhone safe.
Update the iOS software on your iPhone, iPad, or iPod touch
2. Restart your device as the shut down and start up process is important to keep the iOS software running properly. Once you have restarted, then test the Lightning to 3.5 mm Headphone Jack Adapter again with your Beats headphones, as well as another set of headphones to narrow down the issue if it isn’t resolved.
Restart your iPhone, iPad, or iPod touch
Cheers!