diff --git a/README.md b/README.md
index 504ab56..7cf6cb1 100644
--- a/README.md
+++ b/README.md
@@ -167,9 +167,11 @@ cargo run -p lanparty-gateway -- \
 The gateway connects to the relay as `role = gateway`, completes the
 control-stream hello/welcome handshake, opens an AF_PACKET socket on the LAN
 interface with promiscuous packet membership, and bridges Ethernet frames
-between the relay and wired LAN until shutdown. It never fragments Ethernet
-frames; LAN frames whose encoded datagrams exceed the negotiated QUIC budget are
-counted, dropped, and logged instead of stopping the bridge.
+between the relay and wired LAN until shutdown. It captures whole LAN frames up
+to the overlay payload-length ceiling before deciding whether they fit the
+tunnel. It never fragments Ethernet frames; LAN frames whose encoded datagrams
+exceed the negotiated QUIC budget are counted, dropped, and logged instead of
+stopping the bridge.
 `--relay` accepts a DNS name or socket address; bare hosts default to UDP/443.
 It tracks remote-client source MACs seen from relay traffic and periodically
 emits small CAM refresh frames so the physical switch keeps those MACs
diff --git a/crates/lanparty-gateway/src/lib.rs b/crates/lanparty-gateway/src/lib.rs
index 17d9896..74acd19 100644
--- a/crates/lanparty-gateway/src/lib.rs
+++ b/crates/lanparty-gateway/src/lib.rs
@@ -32,8 +32,7 @@ use lanparty_obs::{DropReason, TunnelStats};
 #[cfg(target_os = "linux")]
 use lanparty_obs::{FrameAction, FrameDirection, FrameLog};
 use lanparty_proto::{
-    EthernetFrame, FrameType, MAX_STANDARD_ETHERNET_FRAME_LEN, MacAddr, decode_datagram,
-    encode_datagram, validate_datagram_budget,
+    EthernetFrame, FrameType, MacAddr, decode_datagram, encode_datagram, validate_datagram_budget,
 };
 use quinn::{ClientConfig, Endpoint, crypto::rustls::QuicClientConfig};
 use rustls::pki_types::CertificateDer;
@@ -56,6 +55,13 @@ const CAM_REFRESH_ETHERTYPE: u16 = 0x88b5;
 const CAM_REFRESH_PAYLOAD: &[u8] = b"lanparty-cam-refresh";
 #[cfg(target_os = "linux")]
 const MIN_ETHERNET_FRAME_WITHOUT_FCS: usize = 60;
+#[cfg(target_os = "linux")]
+const LAN_CAPTURE_BUFFER_LEN: usize = u16::MAX as usize;
+#[cfg(target_os = "linux")]
+const _: () = assert!(
+    LAN_CAPTURE_BUFFER_LEN
+        > lanparty_proto::MAX_STANDARD_ETHERNET_FRAME_LEN + lanparty_proto::ETHERNET_HEADER_LEN
+);
 
 #[derive(Debug, Parser)]
 #[command(
@@ -658,7 +664,7 @@ fn gateway_frame_log_line(
 #[cfg(target_os = "linux")]
 async fn read_lan_ethernet(packet_socket: &AsyncFd<PacketSocket>) -> Result<Bytes> {
     loop {
-        let mut buffer = vec![0; MAX_STANDARD_ETHERNET_FRAME_LEN];
+        let mut buffer = vec![0; LAN_CAPTURE_BUFFER_LEN];
         let mut guard = packet_socket
             .readable()
             .await