Problem with physical button volume with naturel option

Hello everyone,
I have been using volumio with Spotify connect for a long time, but now even more because I have switched to qobuz! Besides, I take this opportunity to say what happiness and sound quality with volumio and my audiophonics! But if I come here it’s because I have a little problem. In fact, I pilot volumio from my Android devices, either with the application found on Google play or with the browser, but for both, I cannot change the sound volume with the physical buttons on my phone. I can always turn down without any worries but if I want to go up it always hangs around 24 and I cannot exceed this figure but also using the volume screen icon which allows to increase. Do you have any idea or solution to this problem?
I have tried bubbleupnp and I can control the volume without any problem, I can turn up the sound as I want but still not with volumio. Does anyone have a solution?
With the natural option I have the problem but with linear no problem!
Thank you in advance for your help

Thanks in advance for your help and reply

Volumio Information

Volumio Version:2.861
Hardware: i don’t know where find it
DAC: audiophonics evo sabre