diff --git a/changelog.json b/changelog.json
index d91de9c..85dd1ad 100644
--- a/changelog.json
+++ b/changelog.json
@@ -6,13 +6,15 @@
       "Right-click: update the US county of the selected contacts from the ULS database, replacing a county since renamed or abolished.",
       "A QSO logged from WSJT-X, MSHV or a net now appears in Recent QSOs at once, instead of waiting for a delayed auto-upload to send it.",
       "New installs: the default QSL and recording e-mails end with a credit line and a link to OpsLog. Part of the template, so delete it if unwanted.",
-      "Relay automatic control and band-change messages now follow the Band selector too, so a station without CAT switches its antenna when you change band."
+      "Relay automatic control and band-change messages now follow the Band selector too, so a station without CAT switches its antenna when you change band.",
+      "Fixed OpsLog re-tuning its own rig from its own radio broadcasts, which dropped the CAT link on every JTDX or WSJT-X “Fake It” transmission."
     ],
     "fr": [
       "Clic droit : mettre à jour le comté US des contacts sélectionnés depuis la base ULS, pour remplacer un comté renommé ou supprimé.",
       "Un QSO logué depuis WSJT-X, MSHV ou un net apparaît aussitôt dans les QSO récents, sans attendre l’envoi d’un upload automatique différé.",
       "Nouvelles installations : les mails QSL et enregistrement par défaut finissent par une ligne de crédit et un lien vers OpsLog. Dans le modèle, supprimable.",
-      "Le contrôle automatique des relais et les messages de changement de bande suivent aussi le champ Band : une station sans CAT commute enfin son antenne."
+      "Le contrôle automatique des relais et les messages de changement de bande suivent aussi le champ Band : une station sans CAT commute enfin son antenne.",
+      "Corrigé : OpsLog réaccordait sa propre radio depuis ses propres diffusions, ce qui coupait le lien CAT à chaque émission JTDX ou WSJT-X en « Fake It »."
     ]
   },
   {
diff --git a/internal/integrations/udp/selfecho_test.go b/internal/integrations/udp/selfecho_test.go
new file mode 100644
index 0000000..483d08f
--- /dev/null
+++ b/internal/integrations/udp/selfecho_test.go
@@ -0,0 +1,74 @@
+package udp
+
+import (
+	"net"
+	"testing"
+	"time"
+)
+
+// feed runs one datagram through a remote-call listener and returns the event
+// it produced, or nil.
+func feed(t *testing.T, pkt []byte) *Event {
+	t.Helper()
+	out := make(chan Event, 4)
+	s := &Server{
+		cfg: Config{ID: 1, Name: "DX HUNTER", ServiceType: ServiceRemoteCall, Port: 2241},
+		out: out,
+	}
+	s.handle(pkt, &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 2241})
+	select {
+	case ev := <-out:
+		return &ev
+	case <-time.After(200 * time.Millisecond):
+		return nil
+	}
+}
+
+// A RadioInfo datagram must never be read as a remote-call request.
+//
+// This is the loop from a reported session. An inbound remote-call row and an
+// outbound RadioInfo row shared port 2241, so every datagram OpsLog sent came
+// straight back on the loopback. The tag-stripping heuristic read its last
+// token — <ActiveRadioNr>1</ActiveRadioNr> — as the callsign "1", and <Freq> as
+// a tune request for the frequency the rig was already on.
+//
+// It stayed harmless only while <Freq> was misread as MHz: the tune failed "out
+// of the CAT range" and the loop died there. Reading the unit correctly closed
+// it, and with JTDX "Fake It" — which shifts the dial for every over — each
+// transmission set off a burst of sets echoing between OpsLog and itself until
+// the rig stopped answering IF; and the shared CAT link dropped.
+func TestRadioInfoIsNotARemoteCall(t *testing.T) {
+	pkt := BuildN1MMRadioInfo("F5PHW", 24_915_000, 24_915_000, "FT8", "F5PHW")
+
+	// The trap this closes: the payload really does parse as a plausible dial
+	// frequency, so nothing downstream would have questioned it.
+	m := remoteFreqRe.FindStringSubmatch(string(pkt))
+	if m == nil {
+		t.Fatal("the RadioInfo no longer carries a <Freq> — this test is checking nothing")
+	}
+	if hz := remoteTuneHz(m[1]); hz != 24_915_000 {
+		t.Fatalf("remoteTuneHz(%q) = %d — the dial frequency back is what made the loop live", m[1], hz)
+	}
+
+	if ev := feed(t, pkt); ev != nil {
+		t.Errorf("a RadioInfo produced a remote-call event %+v — the rig would be re-tuned to where it already is", *ev)
+	}
+}
+
+// A callsign has a letter in it. Refusing by shape as well as by name means the
+// next program to broadcast its state on this port cannot drive the rig either.
+func TestRemoteCallNeedsALetter(t *testing.T) {
+	for _, body := range []string{"<CALLSIGN>1</CALLSIGN>", "<CALLSIGN>0</CALLSIGN>", "12345"} {
+		if ev := feed(t, []byte(body)); ev != nil {
+			t.Errorf("%q was accepted as a callsign: %+v", body, *ev)
+		}
+	}
+	// A genuine spot click still gets through, tune request and all.
+	ev := feed(t, []byte("<CALLSIGN>OJ0YL<FREQ>10.112<MODE>CW"))
+	if ev == nil {
+		t.Fatal("a genuine spot click produced no event")
+	}
+	if ev.DXCall != "OJ0YL" || ev.TuneFreqHz != 10_112_000 || ev.TuneMode != "CW" {
+		t.Errorf("spot click decoded as %+v, want OJ0YL / 10112000 Hz / CW", *ev)
+	}
+}
diff --git a/internal/integrations/udp/server.go b/internal/integrations/udp/server.go
index a25365b..cdd38ca 100644
--- a/internal/integrations/udp/server.go
+++ b/internal/integrations/udp/server.go
@@ -423,6 +423,25 @@ func (s *Server) handle(pkt []byte, remote *net.UDPAddr) {
 		// Strip every angle-bracket tag, normalise whitespace, take the
 		// last non-empty token. Upper-case for downstream consistency.
 		text := string(pkt)
+		// NEVER act on an N1MM RadioInfo datagram.
+		//
+		// It is not a spot click, it is a radio TELLING the world where it is —
+		// and on a station where an inbound remote-call row and an outbound
+		// RadioInfo row share a port, the one OpsLog just sent arrives straight
+		// back on the loopback. The tag-stripping below then reads its last token,
+		// <ActiveRadioNr>1</ActiveRadioNr>, as the callsign "1", and <Freq> as a
+		// tune request — for the frequency the rig is already on.
+		//
+		// That was harmless only for as long as <Freq> was misread: in tens of Hz
+		// it looks like a wild number, every tune failed "out of the CAT range",
+		// and the loop died there. Reading the unit correctly closed it. With
+		// WSJT-X/JTDX "Fake It", which shifts the dial for each over, every
+		// transmission then produced a burst of sets echoing between OpsLog and
+		// itself until the rig stopped answering IF; and the shared CAT link
+		// dropped. Reported as Fake It causing CAT disconnections.
+		if low := strings.ToLower(text); strings.Contains(low, "<radioinfo") {
+			return
+		}
 		// Optional tune request: <FREQ>MHz and <MODE>str ride along with the
 		// callsign so a DXHunter spot click can drive OpsLog's CAT. Extract
 		// (and cut) them BEFORE the generic tag-stripping below, which would
@@ -454,7 +473,16 @@ func (s *Server) handle(pkt []byte, remote *net.UDPAddr) {
 		if len(parts) == 0 {
 			return
 		}
-		ev.DXCall = strings.ToUpper(parts[len(parts)-1])
+		call := strings.ToUpper(parts[len(parts)-1])
+		// A callsign has a letter in it. Without this, any status XML that ends
+		// in a number is read as a station — the RadioInfo above was exactly
+		// that, and refusing it by shape as well as by name means the next
+		// program to broadcast its state on this port cannot drive the rig
+		// either.
+		if !strings.ContainsAny(call, "ABCDEFGHIJKLMNOPQRSTUVWXYZ") {
+			return
+		}
+		ev.DXCall = call
 	case ServiceN1MM:
 		adifText, ok, err := ParseN1MM(pkt)
 		if err != nil {
@@ -598,10 +626,36 @@ func (m *Manager) Reload(ctx context.Context) []string {
 		m.inbound[c.ID] = srv
 		m.mu.Unlock()
 	}
+	warnSharedPorts(cfgs)
 	applog.Printf("udp: Reload done — %d server(s) running, %d error(s)", len(m.inbound), len(errs))
 	return errs
 }
 
+// warnSharedPorts names an inbound and an outbound row sitting on the same
+// port, because that is a loop: what OpsLog sends there, OpsLog receives.
+//
+// It is how a station ended up re-tuning its own rig from its own RadioInfo
+// broadcasts. The parser refuses that particular payload now, but the
+// arrangement stays wrong for anything else that lands on the port, and it is
+// invisible in a settings panel that shows one row at a time.
+func warnSharedPorts(cfgs []Config) {
+	in := map[int]string{}
+	for _, c := range cfgs {
+		if c.Enabled && c.Direction != Outbound {
+			in[c.Port] = c.Name
+		}
+	}
+	for _, c := range cfgs {
+		if !c.Enabled || c.Direction != Outbound {
+			continue
+		}
+		if name, ok := in[c.Port]; ok {
+			applog.Printf("udp: %q sends on port %d and %q listens on it — OpsLog will receive its own messages there; give one of the two another port",
+				c.Name, c.Port, name)
+		}
+	}
+}
+
 // Outbound returns the active outbound configs matching a service type.
 // Used by the QSO save path to push notifications to listeners.
 func (m *Manager) Outbound(service ServiceType) []Config {