Just want to warn you, I experienced pretty straight forward bug/scenario, where my existing Win10 1803 builds connects successfully, but if I upgrade to 1903 or install new machine with 1903, VPN connection will not established. The error is typically
something about phonebook file :D ... I just re-installed failed 1903 machine back to 1803 build and it works like a charm again.
MCSE Mobility 2018. Expert on SCCM, Windows 10, ALOVPN, MBAM.