Hi
Try cleaning the lightning connector with cotton buds and isopropyl alcohol to clean off any debris that our human eyes can see
Also try cleaning your lighting port with a sewing needle as it’s surprising how much dirt can hide in there
Also make sure your audio is on stereo but doing this
Settings>accessibility>audio/visual>Scroll down to balance and make sure it’s in the middle
If these methods don’t work inspect the cable for discolouration,cracks and bends And let me know about them so we can adress them accordingly
Hopefully this helps
Thanks:-)