diff --git a/packages/web/src/Router/Route.php b/packages/web/src/Router/Route.php
index 53160071de..4f6cacf36f 100644
--- a/packages/web/src/Router/Route.php
+++ b/packages/web/src/Router/Route.php
@@ -913,10 +913,24 @@ public function __construct()
         $webrootbase = '/' . ($webrootbase === '' ? '' : $webrootbase . '/');
         self::$_webrootbase = $webrootbase;
 
+        $requripath = strtok((string)self::$requesturi, '?');
         /**
          * If API is not enabled redirect to home page.
+         *
+         * Not the agent routes. FOG_API_ENABLED switches off the REST API
+         * that people and API tokens use; /agent/v1/ is FOG's client
+         * channel, which the setting never governed for the legacy client
+         * (service/*.php) either. Caught here, every fog-agent on a server
+         * with the API off was sent a 308 to the login page and could never
+         * enroll or poll (forum topic 18241). The agent routes keep their
+         * own gate below: enroll issues nothing without an approval, and
+         * everything else needs a certificate bound to a host.
          */
-        if (!self::$ajax && !self::$_enabled) {
+        $isAgentRoute = 0 === strpos(
+            $requripath,
+            $webrootbase . self::AGENT_ROUTE_SEGMENT
+        );
+        if (!self::$ajax && !self::$_enabled && !$isAgentRoute) {
             header(
                 sprintf(
                     'Location: %s://%s%smanagement/index.php',
@@ -975,7 +989,6 @@ public function __construct()
             }
             $unauthexact[] = $webrootbase . ltrim($pluginRoute['path'], '/');
         }
-        $requripath = strtok((string)self::$requesturi, '?');
         $requribase = dirname($requripath);
         $isunauth = in_array($requribase, $unauthprefixes)
             || in_array(rtrim($requripath, '/'), $unauthexact);
diff --git a/tests/agent-routes-ignore-api-switch.test.php b/tests/agent-routes-ignore-api-switch.test.php
new file mode 100644
index 0000000000..50720b7d96
--- /dev/null
+++ b/tests/agent-routes-ignore-api-switch.test.php
@@ -0,0 +1,161 @@
+<?php
+/**
+ * The API switch must not switch off fog-agent.
+ *
+ * While FOG_API_ENABLED is off, Route answers with a 308 to the login page.
+ * That check ran before anything else looked at the path, so it took
+ * /agent/v1/ with it: on a server with the REST API off, every fog-agent was
+ * redirected on enroll and on every poll, and could never join. Reported on
+ * the forum as topic 18241:
+ *
+ *   POST https://192.168.1.100/fog/agent/v1/enroll
+ *   HTTP/1.1 308 Permanent Redirect
+ *   Location: https://192.168.1.100/fog/management/index.php
+ *
+ * The setting governs the REST API that people and API tokens use. The agent
+ * routes are FOG's client channel and have their own gate.
+ *
+ * What this pins, each case in its own process because the gate exits:
+ *
+ * - enroll with the API off is not redirected;
+ * - poll with the API off reaches the agent gate and gets its 401, which
+ *   proves the request got past the switch and still needs a certificate;
+ * - an ordinary API route with the API off is still redirected, so the
+ *   switch still does its job.
+ *
+ * The request statics are preset rather than fed through a CGI environment.
+ * Route's dispatcher reads REQUEST_METHOD through filter_input(), which the
+ * CLI SAPI leaves empty, so no route matches and enroll's handler is never
+ * reached. That is why the enroll case asserts only "not a redirect" and the
+ * poll case carries the proof.
+ *
+ * Usage: php tests/agent-routes-ignore-api-switch.test.php
+ * Exit status 0 = pass, 1 = fail.
+ */
+
+use FOG\Router\Route;
+
+require_once __DIR__ . '/lib/fog-test-harness.php';
+
+$childCase = null;
+foreach (array_slice(isset($argv) ? $argv : [], 1) as $arg) {
+    if (0 === strpos($arg, '--case=')) {
+        $childCase = substr($arg, 7);
+    }
+}
+if (null !== $childCase) {
+    apiSwitchRunChild($childCase);
+    exit(0);
+}
+
+/**
+ * Construct Route for one request and print what it answered. Never
+ * asserts -- the parent owns the verdict.
+ *
+ * Both helpers carry a prefix because phpstan analyses tests/ as one
+ * program, and route-read-path-guards.test.php already declares runChild()
+ * and child(). Unprefixed, phpstan read this file's calls against those
+ * declarations and failed the CI job.
+ *
+ * @param string $case "<FOG_API_ENABLED> <request uri>"
+ *
+ * @return void
+ */
+function apiSwitchRunChild($case)
+{
+    list($flag, $uri) = explode(' ', $case, 2);
+    FogTestHarness::boot('agent-routes-ignore-api-switch');
+    $db = FogTestHarness::fakeDb();
+    $db->responder = function ($sql) use ($flag) {
+        if (false === strpos($sql, 'globalSettings')) {
+            return null;
+        }
+        return [
+            ['settingKey' => 'FOG_API_ENABLED', 'settingValue' => $flag],
+            ['settingKey' => 'FOG_API_TOKEN', 'settingValue' => 'test'],
+            ['settingKey' => 'FOG_WEB_ROOT', 'settingValue' => '/fog/'],
+        ];
+    };
+    foreach (
+        [
+            '_initialized' => true,
+            'requesturi' => $uri,
+            'reqmethod' => 'POST',
+            'post' => true,
+            'ajax' => false,
+            'httpproto' => 'https',
+            'httphost' => '192.168.1.100',
+            'remoteaddr' => '192.168.102.20',
+            'scriptname' => '/fog/api/index.php',
+            'querystring' => '',
+        ] as $property => $value
+    ) {
+        FogTestHarness::setStatic('FOGBase', $property, $value);
+    }
+    ob_start();
+    register_shutdown_function(
+        function () {
+            $body = trim((string)ob_get_clean());
+            echo 'RESULT ' . (int)http_response_code() . ' '
+                . str_replace("\n", ' ', $body) . "\n";
+        }
+    );
+    new Route();
+}
+
+/**
+ * Run one request in a child process.
+ *
+ * @param string $flag FOG_API_ENABLED
+ * @param string $uri  the request uri
+ *
+ * @return array [int status (0 when the child printed nothing), string body]
+ */
+function apiSwitchChild($flag, $uri)
+{
+    $pipes = [];
+    $proc = proc_open(
+        [PHP_BINARY, __FILE__, '--case=' . $flag . ' ' . $uri],
+        [0 => ['pipe', 'r'], 1 => ['pipe', 'w'], 2 => ['pipe', 'w']],
+        $pipes
+    );
+    if (!is_resource($proc)) {
+        return [0, 'SPAWN FAILED'];
+    }
+    fclose($pipes[0]);
+    $out = stream_get_contents($pipes[1]);
+    $err = stream_get_contents($pipes[2]);
+    fclose($pipes[1]);
+    fclose($pipes[2]);
+    proc_close($proc);
+    if (preg_match('/^RESULT (\d+) ?(.*)$/m', (string)$out, $m)) {
+        return [(int)$m[1], $m[2]];
+    }
+    return [0, 'NO RESULT: ' . trim(str_replace("\n", ' | ', $out . ' ' . $err))];
+}
+
+$t = new FogChecks();
+
+list($code, $body) = apiSwitchChild('0', '/fog/agent/v1/enroll');
+$t->check(
+    "enroll with the API off is not redirected (got $code $body)",
+    0 !== $code && ($code < 300 || $code >= 400)
+);
+
+list($code, $body) = apiSwitchChild('0', '/fog/agent/v1/poll');
+$t->check(
+    "poll with the API off reaches the agent gate and gets 401 (got $code)",
+    401 === $code
+);
+$t->check(
+    'and the agent gate is what answered, not a token check',
+    false !== strpos($body, '"reason":"no_client_certificate"')
+);
+
+list($code, $body) = apiSwitchChild('0', '/fog/host');
+$t->check(
+    "an API route with the API off is still redirected (got $code)",
+    308 === $code
+);
+
+$t->finish();