Dang, if you were on NA I'd have a bumper ready for you.
gl+ free bump :)
Go to your local D2R installation folder (.../Diablo II Resurrected/d2r.exe).
Right-click the .exe file and create (3) shortcut to your desktop.
Rename them Asia, Eu, Americas
Right-click the new shortcut, select Properties, and add the desired region command at the very end of the Target field (outside of the quotes).
"... .exe" -address ...
Americas: -address us.actual.battle.net
Europe: -address eu.actual.battle.net
Asia: -address kr.actual.battle.net
Close the window and launch the game.