Someone else mentioned having this problem somewhere, I dunno, Maybe it was you and you're looking for alternative answers....
But if not, Try VPNs, or alternate methods of connecting, perhaps even checking (if you're not the owner of your internet and its control settings) modem/router issues and settings.
as it still sounds like some kinda other factor preventing it. - Perhaps an ad/virus/malware, a browser that doesn't like Itch.io, some anti-virus that is being overzealous because of Itch.io having... well.. rather seemingly "freedom" in content, ISP or router/internet restrictions, etc etc.