@KjKAN, excuse any repeat information.
My partner and I both have the Jabra Enhance Pro 20s from Costco which are the same thing as the ReSound Nexia 9s. I have the Galaxy S23 Ultra and she the Galaxy S24 Ultra. Both of us have had pretty stable operation with the ASHA protocol.
She got her HAs a month ago and just returned from 10 days in Spain where she had no problems with her phone and hearing aids working together. We talked daily. She also got the ReSound PhoneClip+ so she could have hands free. She is on the phone a lot. I asked her to leave LE Audio off as she is not tech savvy. Because we are on different coasts for the next month, still, I can not test the LE Audio mode on her S24 to see if the behavior is any different than on my S23. I am not sure why it would be as we are both running One UI 6.1 and Bluetooth 5.3. She has been very happy with her setup
I stream a lot and I am very happy with the sound my HCP helped tune my fitting to, as well as what I did with my phone too. I can switch between streaming and voice calls well in ASHA mode. I have mostly kept LE Audio off as it is finicky. I have to disconnect then connect the HAs and or turn Bluetooth off and on too frequently for my default patience level. With the ASHA protocol I do this much more seldom. I still use it when I want hands free or just because. I can get clear across the house and down a floor hands free with LE Audio. I love my Jabra (read ReSound) HAs with my S23.
Android 15 beta 2 is out and it has fixes for both dual mode (phones that operate in ASHA and LE Audio modes) as well as a number of LE Audio issues. By the end of the year Samsung One UI 7 may be out with these changes. It sounds promising. I hope to hear feedback from Pixel 8 ReSound or Jabra or Oticon HA users with LE Audio before then.
One thing that should help you. Go to phones Settings and search on “Never Auto Sleeping Apps”. Be sure to add the ReSound Smart 3D app to that list. The app runs in the background even if you kill the app. Mine has currently been running in the background for 85 hours. My HAs kept disconnecting from the app before that. You can check on it by tapping the lower left button of the phone screen (where you can see and kill your apps). In the upper left corner there is some wording about background apps. Select that and you will see the apps running in the background. From there you can actually stop the app.
Enjoy your S24s and Nexias. I think they are great choices.