Fix PC Connectivity & Launcher

My Windows-based desktop shows a “secured connection” yet only a handful of sites load; Epic Games pages time-out completely and the Epic Games Launcher will not sign in. I am on Wi-Fi and every other device in the house works fine, so the fault appears to be isolated to this PC... (Budget: $10 - $30 USD, Jobs: Linux, Network Administration, Network Security, System Admin, Technical Documentation, Technical Support, Troubleshooting, Windows Server)