Can't we transfer save from one computer to another? i've been able to to this with other games.
I tend to switch between laptop and desktop depending one where i am.

yes, also to phone and console. But not hellfire multiplayer unless you use devilutionx

i never use multiplayer, just playing Diablo classic, and Hellfire both single player, but it want transfer saves

Your save game is in the main folder called singleXX.sv and stash.sv (XX is a number depending on the character)
Or for hellfire .hsh
Just copy them, i did the same as you, playing on pc and laptop.

it's hsv not hsh