A critical bug in Windows 11 builds 24H2 and 25H2 is causing users with Ethernet connections to lose internet access after installing updates KB5066835 and KB5065789. Users have reported issues on Microsoft’s Q&A forums, and rolling back the operating system is recommended. Possible fixes include performing a full network reset, flushing DNS and resetting TCP/IP via Command Prompt, editing the registry, and using hardware bypass solutions like USB-to-Ethernet or USB-to-WiFi adapters.