A QUICker SASE client: re-building Proxy Mode

Cloudflare One Client re-built proxy mode to use QUIC streams replaced WireGuard-based L3 tunneling with QUIC L4 proxying using HTTP/3 CONNECT.

Smoltcp was previously used for L4-to-L3 conversion user-space TCP implementation converted application traffic into IP packets for WireGuard.

QUIC is used to carry direct L4 proxy traffic via QUIC streams, cloudflare added QUIC stream usage alongside MASQUE for proxying.

Performance testing showed download and upload speeds doubled and latency decreased internal testing compared new QUIC proxying against prior implementation.

Client versions proxy mode improvements require minimum client version 2025.8.779.0 applies to Windows, macOS, and Linux devices.