diff --git a/README.md b/README.md
index c49f376..c039a73 100644
--- a/README.md
+++ b/README.md
@@ -179,6 +179,11 @@ the widest roll it will accept — the console warns you if you enter anything w
 | DK-11208 | 38 × 90 mm die-cut | Narrower; turn the photo off |
 | DK-11209 | 29 × 62 mm die-cut | Name and host only |
 
+**A DK-22251 must be set as the black/red roll even if nothing on the badge is red.** The printer
+refuses a monochrome job on two-colour tape, saying *Black/Red on White paper is installed now.
+Change it to Monochrome media.* The roll setting controls how the job is built, not just its
+colour.
+
 **Tell it which roll is loaded.** *Roll loaded in the printer* under **Sites → Edit → Printer**
 must match what is physically in the machine. A two-colour job sent to a plain roll is refused
 outright: the printer shows **Wrong Roll Type** and nothing comes out. The setting is separate
@@ -223,8 +228,14 @@ docker compose exec visitor-signin node scripts/printer-status.mjs
 ```
 
 It reports the media width, whether the roll is continuous or die-cut, any error the printer is
-holding, and the roll id that matches. `brother_ql`'s network backend only writes to the socket
-and never reads, which is why a refused job still looks like a success — this asks directly.
+holding, and the roll id that matches.
+
+**It does not work on every printer.** Many Brother network print servers are write-only on port
+9100: they accept jobs but never answer a status request, even though the same printer reports
+happily over USB. The QL-820NWB is one of them. When that happens, **Brother Status Monitor on a
+PC with the printer installed is the thing to use** — it gives the exact reason a job was refused,
+in plain words, which is more than anything on the server can tell you. `brother_ql`'s network
+backend never reads the socket at all, so it reports success no matter what the printer does.
 
 If the printer will not answer, work through the possibilities one at a time:
 
diff --git a/public/js/admin.js b/public/js/admin.js
index a3f9395..8a8fcfb 100644
--- a/public/js/admin.js
+++ b/public/js/admin.js
@@ -847,8 +847,10 @@ function openSiteModal(site) {
          <option value="62" ${site.printer.label !== '62red' ? 'selected' : ''}>62 mm continuous, black only</option>
          <option value="62red" ${site.printer.label === '62red' ? 'selected' : ''}>62 mm continuous, black and red (DK-22251)</option>
        </select></label>
-     <p class="hint">This must match the roll actually in the machine. Send a two-colour job to a
-     plain roll and the printer answers <em>Wrong Roll Type</em> and prints nothing.</p>
+     <p class="hint">This must match the roll actually in the machine, and it matters in both
+     directions. A two-colour job on a plain roll is refused as <em>Wrong Roll Type</em>; a
+     monochrome job on a DK-22251 is refused with <em>Black/Red on White paper is installed
+     now</em>. The DK-22251 needs the two-colour option even when the badge is entirely black.</p>
      <div class="modal-row">
        ${field('Model', 'printerModel', site.printer.model)}
        <label class="modal-field"><span>Rotation</span>
diff --git a/scripts/print-probe.mjs b/scripts/print-probe.mjs
index fdca621..b969ab0 100644
--- a/scripts/print-probe.mjs
+++ b/scripts/print-probe.mjs
@@ -68,7 +68,7 @@ for (const [label, description] of CANDIDATES) {
         '--backend', 'network',
         '--model', site.printer_model || 'QL-820NWB',
         '--printer', target,
-        'print', '--label', label, file,
+        'print', '--label', label, ...(label === '62red' ? ['--red'] : []), file,
       ],
       { stdio: ['ignore', 'pipe', 'pipe'], timeout: config.printing.timeoutMs }
     );
diff --git a/scripts/print-test.mjs b/scripts/print-test.mjs
index ef1c4fc..82f28c2 100644
--- a/scripts/print-test.mjs
+++ b/scripts/print-test.mjs
@@ -73,8 +73,10 @@ const args = [
   '--printer', target,
   'print',
   '--label', label,
-  file,
 ];
+// Required on black/red tape even when the badge is entirely black.
+if (label === '62red') args.push('--red');
+args.push(file);
 
 console.log('');
 console.log(`  running: ${config.printing.command} ${args.join(' ')}`);
diff --git a/scripts/printer-status.mjs b/scripts/printer-status.mjs
index 6954b8d..81f580d 100644
--- a/scripts/printer-status.mjs
+++ b/scripts/printer-status.mjs
@@ -102,6 +102,15 @@ socket.on('connect', () => {
   socket.write(Buffer.alloc(200, 0x00));
   socket.write(Buffer.from([0x1b, 0x40]));
   socket.write(Buffer.from([0x1b, 0x69, 0x53]));
+
+  // Some firmware only answers once it is in raster mode, so ask again that way
+  // before giving up.
+  setTimeout(() => {
+    if (!chunks.length && !socket.destroyed) {
+      socket.write(Buffer.from([0x1b, 0x69, 0x61, 0x01]));
+      socket.write(Buffer.from([0x1b, 0x69, 0x53]));
+    }
+  }, 1500);
 });
 
 socket.on('data', (d) => {
@@ -113,8 +122,20 @@ socket.on('timeout', () => {
   socket.destroy();
   if (!chunks.length) {
     console.error('  The printer accepted the connection but sent nothing back.');
-    console.error('  Some firmware only answers when idle — make sure it is not mid-job,');
-    console.error('  and that nothing else is holding port 9100 open.\n');
+    console.error('');
+    console.error('  Many Brother network print servers are write-only on port 9100: they accept');
+    console.error('  jobs but never report status, even though the same printer answers happily');
+    console.error('  over USB. If this is one of them, no amount of asking will help.');
+    console.error('');
+    console.error('  Read the printer instead from:');
+    console.error('    - the display on the machine itself');
+    console.error('    - Brother Status Monitor, on a PC with the printer installed');
+    console.error('    - the printer\'s own web page, at http://' + host + '/');
+    console.error('');
+    console.error('  Status Monitor in particular gives the exact reason a job was refused,');
+    console.error('  which is more than brother_ql can tell you — its network backend never');
+    console.error('  reads the socket, so it reports success whatever the printer does.');
+    console.error('');
     process.exit(1);
   }
 });
diff --git a/src/printer.js b/src/printer.js
index 6804c31..90394d1 100644
--- a/src/printer.js
+++ b/src/printer.js
@@ -291,6 +291,9 @@ function explainPrintError(output, host) {
   if (/Unknown label|label/i.test(last) && /identifier/i.test(last)) {
     return 'The printer rejected the label size. Check the roll loaded matches the badge settings.';
   }
+  if (/Black\/Red|Monochrome media/i.test(output)) {
+    return 'The printer has a black/red roll loaded but received a monochrome job. Set "Roll loaded in the printer" to the DK-22251 option so the job is built for two-colour tape.';
+  }
   if (/wrong roll|WrongMedia|media/i.test(last)) {
     return 'The printer says the roll is wrong. Check "Roll loaded in the printer" matches what is actually in the machine — a black and red job is refused on a plain roll.';
   }
@@ -336,15 +339,22 @@ export async function printBadge(visit, site) {
   const port = Number(site.printer_port) || 9100;
   const target = `tcp://${site.printer_host}:${port}`;
 
+  const label = labelFor(site);
   const args = [
     '--backend', 'network',
     '--model', site.printer_model || 'QL-820NWB',
     '--printer', target,
     'print',
-    '--label', labelFor(site),
-    file,
+    '--label', label,
   ];
 
+  // brother_ql: "You must use this option when printing on black/red tape, even
+  // when not printing red." Without it the job is built as monochrome, the
+  // printer sees two-colour media, and refuses the whole thing.
+  if (label === '62red') args.push('--red');
+
+  args.push(file);
+
   try {
     await runBrotherQl(args, config.printing.timeoutMs);
     note(site.id, true, `Printed to ${site.printer_host}`);
diff --git a/src/routes/admin.js b/src/routes/admin.js
index ca7efbf..cff3937 100644
--- a/src/routes/admin.js
+++ b/src/routes/admin.js
@@ -539,7 +539,7 @@ router.get('/sites/:id/printer-diagnostics', (req, res) => {
       'brother_ql --backend network',
       `--model ${site.printer_model || 'QL-820NWB'}`,
       `--printer tcp://${site.printer_host}:${site.printer_port || 9100}`,
-      `print --label ${printer.labelFor(site)} badge.png`,
+      `print --label ${printer.labelFor(site)}${printer.labelFor(site) === '62red' ? ' --red' : ''} badge.png`,
     ].join(' '),
   });
 });