diff --git a/app/engine.js b/app/engine.js
index 8bd6f05..6387710 100644
--- a/app/engine.js
+++ b/app/engine.js
@@ -3508,14 +3508,50 @@ function shareChoice() {
   };
 }
 
-function shareBase() {
+/* This Mac on the church network. The operator page lives here and NOWHERE
+   else: it returns 404 to anything arriving through a proxy, by design. */
+function lanBase() {
   const c = shareChoice();
   if (!c || c.none) return '';
   return 'http://' + c.addr.address + ':' + state.local.port;
 }
 
+/*
+ * WHAT THE CONGREGATION OPENS.
+ *
+ * A church that has put this on a domain has said so in the operator page's
+ * Public address, and from that moment the LAN address is the wrong thing to
+ * print: it is not what is on the poster, not what the QR should encode, and
+ * not what someone off the building's wifi can reach. The app window went on
+ * showing the IP anyway, because this half of it never read that setting --
+ * the operator page honoured it and the main window did not, so the two
+ * disagreed about the one fact they both exist to display.
+ */
+function publicBaseConfigured() {
+  const u = opConfig && typeof opConfig.publicUrl === 'string' ? opConfig.publicUrl.trim() : '';
+  return u ? u.replace(/\/+$/, '') : '';
+}
+
+function shareBase() {
+  return publicBaseConfigured() || lanBase();
+}
+
 function renderQrWarning() {
   const el = $('qrWarn');
+  /*
+   * On a domain the warnings below are about an address nobody is being
+   * given any more. Saying "Wi-Fi is down, phones cannot reach the code"
+   * while the code points at a proxy would send the desk after the wrong
+   * thing entirely.
+   */
+  const pub = publicBaseConfigured();
+  if (pub) {
+    el.hidden = false;
+    el.textContent = 'The code points at ' + pub + ', set as the public address. ' +
+      'This Mac still has to be reachable from there; its own address is ' +
+      (lanBase() || 'unavailable') + '.';
+    return;
+  }
   const c = shareChoice();
   if (!c) { el.hidden = true; return; }
 
@@ -3665,7 +3701,8 @@ function renderBuildTag() {
 }
 
 function renderOperatorUrl() {
-  const base = shareBase();
+  /* Deliberately lanBase, not shareBase: over a proxy /operator is a 404. */
+  const base = lanBase();
   $('opPageUrl').textContent = base ? base + '/operator' : 'no network';
 }
 
@@ -3968,6 +4005,7 @@ async function loadOperator() {
   try {
     const j = await opApi('/api/config');
     opConfig = j.config;
+    renderShare();   /* publicUrl may have just arrived */
     clearTimeout(opLoadTimer); opLoadTimer = null;   // it answered; stop retrying
     opRetryMs = 0;
     renderOpLanguages();
@@ -4022,6 +4060,7 @@ async function opSave(patch, okMsg) {
   try {
     const j = await opApi('/api/config', { method: 'POST', body: JSON.stringify(patch) });
     opConfig = j.config;
+    renderShare();   /* publicUrl may have just arrived */
     if (okMsg) log(okMsg, 'ok');
     return j;
   } catch (e) { log('could not save: ' + e.message, 'err'); throw e; }
diff --git a/app/package.json b/app/package.json
index cb1a4ca..e2ff77e 100644
--- a/app/package.json
+++ b/app/package.json
@@ -2,7 +2,7 @@
   "name": "church-translate-engine",
   "productName": "Church Translate",
   "version": "3.23.2",
-  "buildNumber": 121,
+  "buildNumber": 122,
   "private": true,
   "description": "Live sermon translation — self-contained: captures audio, transcribes, translates, and serves the congregation page itself",
   "main": "main.js",
@@ -106,7 +106,7 @@
       ]
     },
     "asar": false,
-    "buildVersion": "121",
+    "buildVersion": "122",
     "win": {
       "target": [
         {