If you have default homepage set to index.aspx make sure to use sample code in web.config with the help of your developer as follows:
<system.webServer>
<defaultDocument>
<files>
<clear />
<add value="index.aspx"/>
</files>
</defaultDocument>
</system.webServer>
The file name shall be used as default.aspx if your homepage you want to set as default.aspx instead of index.aspx as filename depends on your developer's decision, what file name they used to make your website codes for homepage.
