Post-quantum TLS breaks connections on Windows servers due to NIC offload bug

The larger ClientHello with the post-quantum X25519MLKEM768 key share no longer fits in one TCP packet, and Receive Segment Coalescing on NICs (NVIDIA/Mellanox ConnectX-4 Lx, WinOF-2 driver 2.42) merges the segments with a corrupted TCP timestamp field. Windows then drops roughly half of handshakes, so phones hit ERR_CONNECTION_RESET. Fixes: disable RSC via netsh or strip the timestamp option from SYN packets at the network edge.

• Chrome, Edge and Firefox add X25519MLKEM768 to TLS 1.3, growing ClientHello to ~1.8 KB
• RSC on ConnectX-4 Lx cards clears the top bit of the TCP timestamp, so PAWS drops the segment
• About 50% of connections fail because timestamps start at a random value
• Fix: netsh int tcp set global rsc=disabled or strip timestamps from SYNs at the router