How old is he? Might still be possible to train him.

is he quiet at all when he’s alone? You could try only going out there when he’s quiet, even if it’s just for a second, and rewarding him, and ignore the crying (easier said than done, I know), and eventually he should do it less and less

though of course some of it is individual personality too and if he’s particularly bonded to you or another dog or whoever, sometimes they can separation anxiety if you leave. Gator wa slike that a little cause he loved my brother sooooo much.

he also trained us to give him attention when he grumbled which eventually turned to barking
