quick google search found this
https://archive.org/details/diablo2patchesso download some disc .iso's from another archive, like
https://archive.org/details/diablo-ii-plus-expansionuse a virtual drive to mount the .iso files, install d2 or d2+lod, then run the appropriate patch.exe file for your install. if you install just d2 (classic) you'll use the D2_1xx.exe and if you install LoD you'll use LODPatch_1xx.exe. you probably want a classic d2 install with a 1.06 patch
no i have not done this personally so do not ask me for a detailed tutorial. this should work with single player, might work with local LAN multiplayer (install same version on 2 pcs), i doubt it will work with open or closed battle.net and if you try it might just patch you to the current patch anyway.
if i were you and i wanted to play og d2 1.06 with friend(s) (assuming you have any who would do this with you), i would get a couple identical cheap refurbished laptops, pirate windows xp, install and patch d2, then set them up on a dedicated private (not connected to outside internet) LAN network.
on the off chance that you actually try this, let me know if it works. i dont have any friends, much less any cool enough to want to play outdated versions of a decades-old game together. but i have a cousin or two whom i see every so many years i could probably goad them into a challenge of prelod pvp ability