diff --git a/drb-edge-node/app/internal/mqtt_manager.py b/drb-edge-node/app/internal/mqtt_manager.py
index 73aba28..f7e3030 100644
--- a/drb-edge-node/app/internal/mqtt_manager.py
+++ b/drb-edge-node/app/internal/mqtt_manager.py
@@ -236,6 +236,12 @@ class MQTTManager:
         }
         payload["sdr_pins"] = config.sdr_pins
         secondary = await secondary_sdr_client.status()
+        # Unreachable secondary-sdr: say so with explicit nulls. C2 only
+        # overwrites keys present in the checkin, so omitting them would leave
+        # a dead decoder showing "Running" forever.
+        payload["secondary_sdr_running"] = None
+        payload["sdr_devices"] = None
+        payload["op25_sdr_serial"] = None
         if secondary is not None:
             payload["secondary_sdr_running"] = [r["mode"] for r in secondary.get("running", [])]
             if secondary.get("devices") is not None:
diff --git a/drb-edge-node/app/templates/index.html b/drb-edge-node/app/templates/index.html
index de7e04e..cfe08d5 100644
--- a/drb-edge-node/app/templates/index.html
+++ b/drb-edge-node/app/templates/index.html
@@ -568,7 +568,8 @@
       return `<option value="">${esc(autoLabel)}</option>` +
         devs.map(d => `<option value="${esc(d.serial)}" ${d.serial === selected ? 'selected' : ''}>` +
           `SDR ${d.index + 1} · serial ${esc(d.serial)}${d.duplicate_serial ? ' (shared serial!)' : ''}</option>`).join('') +
-        (selected && !known ? `<option value="${esc(selected)}" selected>serial ${esc(selected)} (not plugged in)</option>` : '');
+        (selected && !known ? `<option value="${esc(selected)}" selected>serial ${esc(selected)} ` +
+          `(${sdr.devices === null ? 'not reported' : 'not plugged in'})</option>` : '');
     }
 
     function renderSdr() {
@@ -585,7 +586,7 @@
       const running = sdr.running || [];
       sdrRows.forEach((row, i) => {
         const [name, hint] = SDR_LABELS[row.mode] || [row.mode, ''];
-        const pinMissing = row.pin && !(sdr.devices || []).some(d => d.serial === row.pin);
+        const pinMissing = row.pin && sdr.devices !== null && !sdr.devices.some(d => d.serial === row.pin);
         const state = !row.enabled ? 'Off'
           : sdrDirty ? 'Unsaved'
           : sdr.running === null ? 'Unknown'