As discussed in the comments, installing new fonts on a Windows server typically requires a restart.
Without a restart, only the current session is notified of the new font. Other sessions, such as ASP.NET, are not notified, and will not be able to use the new font.
It is
sometimes possible to avoid a restart by calling
AddFontResource[
^] from code executing within the target session. But in my experience, you still need to at least restart IIS for the changes to get picked up.