Call hangs up after 8 Hours for no reason

Ive been having issues with my phone calls lately where my calls end at exactly 8 Hours and 1 minute. My internet is perfectly fine and usually at 3 or 4 bars. Along with checking with my internet provider, Ive also freed up storage space. I’ve searched around and still can’t find an answer on why my phone does this, is there anything I can do to extend my calls?