diff --git a/crates/fbuild-daemon/src/handlers/operations/deploy.rs b/crates/fbuild-daemon/src/handlers/operations/deploy.rs
index 8cf16d49..4d0b17c4 100644
--- a/crates/fbuild-daemon/src/handlers/operations/deploy.rs
+++ b/crates/fbuild-daemon/src/handlers/operations/deploy.rs
@@ -1107,6 +1107,8 @@ pub async fn deploy(
             r.message,
         ),
         Ok(r) => {
+            let mut failure_stderr = Some(r.stderr);
+            append_warning_to_stderr(&mut failure_stderr, deploy_port_warning);
             return (
                 StatusCode::INTERNAL_SERVER_ERROR,
                 Json(OperationResponse {
@@ -1119,13 +1121,14 @@ pub async fn deploy(
                     output_dir: reported_output_dir.clone(),
                     launch_url: None,
                     stdout: Some(r.stdout),
-                    stderr: Some(r.stderr),
+                    stderr: failure_stderr,
                 }),
             );
         }
         Err(e) => {
             let mut response = deploy_error_response(request_id, &e);
             response.usb_recovery = usb_recovery_request;
+            append_warning_to_stderr(&mut response.stderr, deploy_port_warning);
             return (StatusCode::INTERNAL_SERVER_ERROR, Json(response));
         }
     };
diff --git a/crates/fbuild-daemon/src/handlers/operations/deploy_port.rs b/crates/fbuild-daemon/src/handlers/operations/deploy_port.rs
index c7f06e01..5dc5c3f2 100644
--- a/crates/fbuild-daemon/src/handlers/operations/deploy_port.rs
+++ b/crates/fbuild-daemon/src/handlers/operations/deploy_port.rs
@@ -55,9 +55,27 @@ fn choose_deploy_port_with_profile_lookup(
     if platform == Platform::RaspberryPi {
         let expected_generation = rp_generation_for(board);
         let board_profile = rp_board_profile_id(board_id, board).and_then(profile_lookup);
+        let mismatched = if board_profile.is_some() {
+            rp_generation_mates(
+                &devices,
+                expected_generation,
+                fbuild_core::usb::profiles::profiles_for,
+            )
+        } else {
+            Vec::new()
+        };
         let (matches, unhealthy) =
             partition_rp_candidates_for_board(devices, board_profile.as_ref(), expected_generation);
-        return rp_deploy_choice(matches, unhealthy);
+        let no_exact_match = matches.is_empty();
+        let mut choice = rp_deploy_choice(matches, unhealthy);
+        if no_exact_match && !mismatched.is_empty() {
+            let note = identity_mismatch_note(board_id, &mismatched);
+            choice.warning = Some(match choice.warning.take() {
+                Some(existing) => format!("{existing}; {note}"),
+                None => note,
+            });
+        }
+        return choice;
     }
 
     let mut candidates: Vec<_> = devices
@@ -115,6 +133,34 @@ fn choose_deploy_port_with_profile_lookup(
     }
 }
 
+/// Healthy connected RP-generation CDC ports whose observed identity is not
+/// the requested board's. They are never auto-selected (W and non-W stay
+/// distinct), but naming them turns a bare "no port" into an actionable
+/// diagnosis (FastLED/fbuild#1430).
+fn rp_generation_mates(
+    devices: &[DeviceState],
+    expected: RpGeneration,
+    profiles_of: impl Fn(u16, u16) -> Vec<fbuild_core::usb::profiles::UsbTransportProfile>,
+) -> Vec<String> {
+    devices
+        .iter()
+        .filter(|device| device.is_connected && !device.port_health.is_known_unhealthy())
+        .filter_map(|device| {
+            let (vid, pid) = device.vid.zip(device.pid)?;
+            rp_profiles_match_generation(&profiles_of(vid, pid), expected)
+                .then(|| format!("{} ({vid:04x}:{pid:04x})", device.port))
+        })
+        .collect()
+}
+
+fn identity_mismatch_note(board_id: Option<&str>, mates: &[String]) -> String {
+    format!(
+        "connected RP-series CDC port(s) {} are running firmware whose USB identity does not match {}'s runtime identity; a running image's identity reflects the last firmware flashed, not the board, so fbuild will not auto-select it — pass -p/--port <port> to deploy anyway",
+        mates.join(", "),
+        board_id.unwrap_or("the target environment"),
+    )
+}
+
 fn rp_board_profile_id<'a>(
     board_id: Option<&'a str>,
     board: Option<&'a BoardConfig>,
@@ -563,6 +609,30 @@ mod tests {
         }
     }
 
+    #[test]
+    fn identity_mismatch_names_the_attached_port_and_the_remedy() {
+        let pico = runtime_profile(Some("raspberrypi"), Some("rp2350"), false);
+        let mates = rp_generation_mates(
+            &[
+                device("/dev/ttyACM0", Some(0x2E8A), Some(0x000F)),
+                device("/dev/ttyACM2", Some(0x303A), Some(0x1001)),
+            ],
+            RpGeneration::Rp2350,
+            |vid, _| {
+                if vid == 0x2E8A {
+                    vec![pico.clone()]
+                } else {
+                    Vec::new()
+                }
+            },
+        );
+        assert_eq!(mates, vec!["/dev/ttyACM0 (2e8a:000f)".to_string()]);
+        let note = identity_mismatch_note(Some("rpipico2w"), &mates);
+        assert!(note.contains("/dev/ttyACM0"), "{note}");
+        assert!(note.contains("rpipico2w"), "{note}");
+        assert!(note.contains("-p/--port"), "{note}");
+    }
+
     #[test]
     fn raspberry_pi_runtime_selection_falls_back_when_profile_is_unavailable() {
         let pico = runtime_profile(Some("raspberrypi"), Some("rp2040"), false);