The difference between the two was supposed to be that WNetGetConnection required the drive to be actively connected, but sure if you want to switch that in and let me know if it works?

Error 234 is ERROR_MORE_DATA so it must behave contrary to documentation and append the data pointed to into the return...

Code:
Dim bt() As Byte
ReDim bt((MAX_PATH * 2 + 1) + LenB(tn))
lRet = WNetGetUniversalNameW(StrPtr("L:\"), UNIVERSAL_NAME_INFO_LEVEL, bt(0), UBound(bt) + 1)
If lRet = 0 Then
    CopyMemory tn, bt(0), LenB(tn)
    Dim sPath As String
    sPath = PointerToStringW(tn.lpUniversalName)
    Debug.Print sPath
End If