diff --git a/monitor.py b/monitor.py
index 3a12544..9effb14 100644
--- a/monitor.py
+++ b/monitor.py
@@ -559,9 +559,11 @@ class LinkStatsCollector:
             host_ip = instance.split(':')[0]
             ifaces  = list(iface_metrics.keys())
 
-            # SSH ethtool collection via Pulse worker (one connection per host, all ifaces)
+            # SSH ethtool collection via Pulse worker — only for explicitly configured
+            # hosts (instance_map keys).  Hosts like postgresql/matrix may report
+            # node_exporter metrics to Prometheus but don't need link diagnostics.
             ethtool_data: Dict[str, dict] = {}
-            if self.pulse.url and ifaces:
+            if self.pulse.url and ifaces and instance in instance_map:
                 try:
                     ethtool_data = self._ssh_batch(host_ip, ifaces)
                 except Exception as e: