diff --git a/src/Cli/Commands/ServerDiagnoseCommand.php b/src/Cli/Commands/ServerDiagnoseCommand.php
index 09e49332..beba67b3 100644
--- a/src/Cli/Commands/ServerDiagnoseCommand.php
+++ b/src/Cli/Commands/ServerDiagnoseCommand.php
@@ -4,6 +4,7 @@ namespace XcVm\Cli\Commands;
 
 use XcVm\Cli\CommandInterface;
 use XcVm\Cli\CronJobs\ServersCronJob;
+use XcVm\Core\Config\OpensslExtra;
 use XcVm\Core\Config\SettingsManager;
 use XcVm\Core\Util\Encryption;
 use XcVm\Domain\Server\ServerRepository;
@@ -78,13 +79,13 @@ class ServerDiagnoseCommand implements CommandInterface {
 			echo "Server #{$rTargetID} is the MAIN server — nothing to diagnose (it is always 'online' to itself).\n";
 			return 0;
 		}
-		return $this->diagnoseFromMain($rServers[$rTargetID], $rTargetID);
+		return $this->diagnoseFromMain($rServers[$rTargetID], $rTargetID, $this->findMain($rServers));
 	}
 
 	// ─────────────────────────────────────────────────────────────────────────
 	//  Mode A — remote probe from the MAIN
 	// ─────────────────────────────────────────────────────────────────────────
-	private function diagnoseFromMain(array $rServer, int $rServerID): int {
+	private function diagnoseFromMain(array $rServer, int $rServerID, ?array $rMain): int {
 		self::db();
 
 		$rIP   = (string) $rServer['server_ip'];
@@ -118,6 +119,7 @@ class ServerDiagnoseCommand implements CommandInterface {
 
 		$this->clockSection($rServer, $rProblems);
 		$this->signalSection($rServerID, $rNow, $rProblems);
+		$this->opensslExtraSection($rServer, $rMain, $rProblems);
 		return $this->summary($rProblems);
 	}
 
@@ -223,6 +225,9 @@ class ServerDiagnoseCommand implements CommandInterface {
 		// 7. Clock.
 		$this->clockSection($rMe, $rProblems);
 
+		// 8. Do tokens minted on the main open here?
+		$this->opensslExtraSection($rMe, $rMain, $rProblems);
+
 		return $this->summary($rProblems);
 	}
 
@@ -270,6 +275,27 @@ class ServerDiagnoseCommand implements CommandInterface {
 		}
 	}
 
+	/**
+	 * Compare the OPENSSL_EXTRA fingerprints the node and the main publish in
+	 * server_hardware (cron:servers). Proxies publish none and are skipped.
+	 */
+	private function opensslExtraSection(array $rServer, ?array $rMain, array &$rProblems): void {
+		if ($rMain === null || (int) ($rServer['server_type'] ?? 0) === 1) {
+			return;
+		}
+		$rNodePrint = OpensslExtra::reportedFingerprint($rServer);
+		$rMainPrint = OpensslExtra::reportedFingerprint($rMain);
+		if ($rNodePrint === null || $rMainPrint === null) {
+			$this->line('OPENSSL_EXTRA', 'unknown (' . ($rNodePrint === null ? 'node' : 'main') . ' not updated)', true);
+			return;
+		}
+		$rOk = hash_equals($rMainPrint, $rNodePrint);
+		$this->line('OPENSSL_EXTRA', $rOk ? 'matches main' : 'MISMATCH with main', $rOk);
+		if (!$rOk) {
+			$rProblems[] = 'OPENSSL_EXTRA mismatch: tokens minted on MAIN are rejected by this node (playback redirected from the main fails).';
+		}
+	}
+
 	private function summary(array $rProblems): int {
 		echo str_repeat('-', 64) . "\n";
 		if ($rProblems === []) {
diff --git a/src/Cli/CronJobs/ServersCronJob.php b/src/Cli/CronJobs/ServersCronJob.php
index 31811706..a309df17 100644
--- a/src/Cli/CronJobs/ServersCronJob.php
+++ b/src/Cli/CronJobs/ServersCronJob.php
@@ -4,6 +4,7 @@ namespace XcVm\Cli\CronJobs;
 
 use XcVm\Cli\CommandInterface;
 use XcVm\Cli\CronTrait;
+use XcVm\Core\Config\OpensslExtra;
 use XcVm\Core\Config\SettingsManager;
 use XcVm\Core\Config\SettingsRepository;
 use XcVm\Core\Process\ProcessManager;
@@ -156,6 +157,8 @@ class ServersCronJob implements CommandInterface {
 		}
 
 		$rHardware = ['total_ram' => $rStats['total_mem'], 'total_used' => $rStats['total_mem_used'], 'cores' => $rStats['cpu_cores'], 'threads' => $rStats['cpu_cores'], 'kernel' => $rStats['kernel'], 'total_running_streams' => $rStats['total_running_streams'], 'cpu_name' => $rStats['cpu_name'], 'cpu_usage' => $rStats['cpu'], 'network_speed' => $rStats['network_speed'], 'bytes_sent' => $rStats['bytes_sent'], 'bytes_received' => $rStats['bytes_received']];
+		// Lets server:diagnose tell whether this node reads MAIN's tokens (never the value itself).
+		$rHardware[OpensslExtra::HARDWARE_KEY] = OpensslExtra::fingerprint(OPENSSL_EXTRA);
 
 		if (@fsockopen($rServers[SERVER_ID]['server_ip'], $rServers[SERVER_ID]['http_broadcast_port'], $rErrNo, $rErrStr, 3) || @fsockopen($rServers[SERVER_ID]['server_ip'], $rServers[SERVER_ID]['https_broadcast_port'], $rErrNo, $rErrStr, 3)) {
 			$rRemoteStatus = true;
diff --git a/src/Core/Config/OpensslExtra.php b/src/Core/Config/OpensslExtra.php
new file mode 100644
index 00000000..fb08889d
--- /dev/null
+++ b/src/Core/Config/OpensslExtra.php
@@ -0,0 +1,46 @@
+<?php
+
+namespace XcVm\Core\Config;
+
+/**
+ * OPENSSL_EXTRA across the cluster.
+ *
+ * OPENSSL_EXTRA (ConstantsInitializer::resolveOpensslExtra: config/openssl_extra,
+ * else the built-in default) keys stream tokens, hmac_keys and image-cache
+ * names. A MAIN and its LBs must hold the same value: a token MAIN mints for a
+ * redirect is read on the LB with the LB's value. A MAIN set up by the current
+ * installer holds a random value, while an LB added with server:install does
+ * not get that file and runs on the default.
+ *
+ * Each node publishes a fingerprint of its value (never the value) in
+ * servers.server_hardware, so server:diagnose can compare them.
+ *
+ * @package XC_VM_Core_Config
+ * @author  Divarion_D <https://github.com/Divarion-D>
+ * @copyright 2025-2026 Vateron Media
+ * @link    https://github.com/Vateron-Media/XC_VM
+ * @license AGPL-3.0 https://www.gnu.org/licenses/agpl-3.0.html
+ */
+final class OpensslExtra {
+	/** The server_hardware key cron:servers publishes the fingerprint under. */
+	public const HARDWARE_KEY = 'openssl_extra_fp';
+
+	/**
+	 * A fingerprint of $rValue that can be compared across nodes: an HMAC keyed
+	 * by the value, cut to 64 bits. It does not reveal the value.
+	 */
+	public static function fingerprint(string $rValue): string {
+		return substr(hash_hmac('sha256', 'xc_vm openssl_extra fingerprint v1', $rValue), 0, 16);
+	}
+
+	/**
+	 * The fingerprint a server row publishes, or null when it publishes none
+	 * (a proxy, or a node that has not been updated).
+	 */
+	public static function reportedFingerprint(array $rServer): ?string {
+		$rHardware = json_decode((string) ($rServer['server_hardware'] ?? ''), true);
+		$rPrint = is_array($rHardware) ? ($rHardware[self::HARDWARE_KEY] ?? null) : null;
+
+		return (is_string($rPrint) && $rPrint !== '') ? $rPrint : null;
+	}
+}
diff --git a/tests/Unit/OpensslExtraTest.php b/tests/Unit/OpensslExtraTest.php
new file mode 100644
index 00000000..5b4531b9
--- /dev/null
+++ b/tests/Unit/OpensslExtraTest.php
@@ -0,0 +1,39 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+use XcVm\Core\Config\OpensslExtra;
+
+/**
+ * OpensslExtra — a MAIN and its LBs must hold the same OPENSSL_EXTRA, or the
+ * tokens MAIN mints for its redirects are rejected by the LB.
+ *
+ * fingerprint / reportedFingerprint: what each node publishes in
+ * servers.server_hardware, so the values can be compared without leaving the
+ * node.
+ */
+final class OpensslExtraTest extends TestCase {
+
+	public function testFingerprintIsAShortStableDigestThatHidesTheValue(): void {
+		$rSecret = 'fNiu3XD448xTDa27xoY4';
+		$rPrint = OpensslExtra::fingerprint($rSecret);
+
+		$this->assertSame($rPrint, OpensslExtra::fingerprint($rSecret));
+		$this->assertMatchesRegularExpression('/^[0-9a-f]{16}$/', $rPrint);
+		$this->assertNotSame(OpensslExtra::fingerprint('a'), OpensslExtra::fingerprint('b'));
+		$this->assertStringNotContainsString($rSecret, $rPrint);
+		$this->assertNotSame(substr(hash('sha256', $rSecret), 0, 16), $rPrint, 'keyed, not a bare hash of the value');
+		$this->assertNotSame(substr(md5($rSecret), 0, 16), $rPrint);
+	}
+
+	public function testReportedFingerprintIsReadFromServerHardware(): void {
+		$rPrint = OpensslExtra::fingerprint('x');
+
+		$this->assertSame($rPrint, OpensslExtra::reportedFingerprint(['server_hardware' => json_encode(['cores' => 4, OpensslExtra::HARDWARE_KEY => $rPrint])]));
+		$this->assertNull(OpensslExtra::reportedFingerprint(['server_hardware' => json_encode(['cores' => 4])]), 'node not updated yet');
+		$this->assertNull(OpensslExtra::reportedFingerprint(['server_hardware' => json_encode([OpensslExtra::HARDWARE_KEY => ''])]));
+		$this->assertNull(OpensslExtra::reportedFingerprint(['server_hardware' => json_encode([OpensslExtra::HARDWARE_KEY => 12])]));
+		$this->assertNull(OpensslExtra::reportedFingerprint(['server_hardware' => 'not json']));
+		$this->assertNull(OpensslExtra::reportedFingerprint(['server_hardware' => null]));
+		$this->assertNull(OpensslExtra::reportedFingerprint([]));
+	}
+}
diff --git a/tests/Unit/ServerDiagnoseOpensslExtraTest.php b/tests/Unit/ServerDiagnoseOpensslExtraTest.php
new file mode 100644
index 00000000..51d7ad5e
--- /dev/null
+++ b/tests/Unit/ServerDiagnoseOpensslExtraTest.php
@@ -0,0 +1,64 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+use XcVm\Cli\Commands\ServerDiagnoseCommand;
+use XcVm\Core\Config\OpensslExtra;
+
+/**
+ * server:diagnose — compares the OPENSSL_EXTRA fingerprint a node publishes in
+ * server_hardware with the MAIN's. A mismatch means every token MAIN mints for
+ * a redirect is rejected by that node. A node that publishes none runs an
+ * older build; proxies publish none and are not checked.
+ */
+final class ServerDiagnoseOpensslExtraTest extends TestCase {
+
+	private function row(int $rID, ?string $rValue, array $rOverride = []): array {
+		$rHardware = ['cores' => 4];
+		if ($rValue !== null) {
+			$rHardware[OpensslExtra::HARDWARE_KEY] = OpensslExtra::fingerprint($rValue);
+		}
+
+		return array_merge(['id' => $rID, 'is_main' => (int) ($rID === 1), 'server_type' => 0, 'server_hardware' => json_encode($rHardware)], $rOverride);
+	}
+
+	/** @return array{0:string,1:string[]} [output, problems] */
+	private function check(array $rServer, ?array $rMain): array {
+		$rMethod = new ReflectionMethod(ServerDiagnoseCommand::class, 'opensslExtraSection');
+		$rMethod->setAccessible(true);
+		$rProblems = [];
+		ob_start();
+		$rMethod->invokeArgs(new ServerDiagnoseCommand(), [$rServer, $rMain, &$rProblems]);
+
+		return [(string) ob_get_clean(), $rProblems];
+	}
+
+	public function testAMismatchIsReportedAsAProblem(): void {
+		[$rOutput, $rProblems] = $this->check($this->row(2, 'fNiu3XD448xTDa27xoY4'), $this->row(1, 'random-main-extra'));
+
+		$this->assertStringContainsString('[WARN]', $rOutput);
+		$this->assertCount(1, $rProblems);
+		$this->assertStringStartsWith('OPENSSL_EXTRA mismatch: tokens minted on MAIN are rejected by this node', $rProblems[0]);
+	}
+
+	public function testMatchingValuesPass(): void {
+		[$rOutput, $rProblems] = $this->check($this->row(2, 'same-extra'), $this->row(1, 'same-extra'));
+
+		$this->assertStringContainsString('[OK]', $rOutput);
+		$this->assertSame([], $rProblems);
+	}
+
+	public function testAMissingFingerprintReadsAsUnknown(): void {
+		[$rOutput, $rProblems] = $this->check($this->row(2, null), $this->row(1, 'main-extra'));
+		$this->assertStringContainsString('unknown (node not updated)', $rOutput);
+		$this->assertSame([], $rProblems);
+
+		[$rOutput, $rProblems] = $this->check($this->row(2, 'lb-extra'), $this->row(1, null));
+		$this->assertStringContainsString('unknown (main not updated)', $rOutput);
+		$this->assertSame([], $rProblems);
+	}
+
+	public function testProxiesAndAMissingMainAreSkipped(): void {
+		$this->assertSame(['', []], $this->check($this->row(3, null, ['server_type' => 1]), $this->row(1, 'main-extra')));
+		$this->assertSame(['', []], $this->check($this->row(2, 'lb-extra'), null));
+	}
+}