As well as checking the file paths for the stylesheet and the font files, you'll also need to check the MIME type mapping. IIS doesn't include MIME types for web fonts by default.
This is the
web.config
file I'm currently using for a fonts directory:
<configuration>
<system.webServer>
<staticContent>
<mimeMap fileExtension="eot" mimeType="application/vnd.ms-fontobject" />
<mimeMap fileExtension="otf" mimeType="application/x-font-opentype" />
<mimeMap fileExtension="svg" mimeType="image/svg+xml" />
<mimeMap fileExtension="ttf" mimeType="application/x-font-truetype" />
<mimeMap fileExtension="woff" mimeType="application/font-woff" />
<mimeMap fileExtension="woff2" mimeType="application/font-woff2" />
</staticContent>
</system.webServer>
</configuration>