Hi @tezalsec,
Thanks for pointing this out and for providing detailed information about your server configuration and the challenges with .ico files.
Currently, MainWP fetches favicon files directly as they exist on child sites, which means if a child site has .ico files for favicons, that’s what gets retrieved and displayed without any conversion.
However, you can manually upload a custom icon on the Edit page of a Child site. This way, you can bypass .ico files altogether by providing a .png or other preferred file formats directly.
To address your suggestion of always using .png for favicons by converting .ico, you’re welcome to submit this as a feature request on our Feedback Site. That helps us gauge user interest and prioritize potential changes.