diff --git a/src/network/networkd-sysctl.c b/src/network/networkd-sysctl.c
index ba90d342c5..c59cb2a5d7 100644
--- a/src/network/networkd-sysctl.c
+++ b/src/network/networkd-sysctl.c
@@ -545,11 +545,11 @@ int link_set_ipv6_mtu(Link *link, int log_level) {
         if (mtu == 0)
                 return 0;
 
-        if (mtu > link->max_mtu) {
+        if (mtu > link->mtu) {
                 log_link_full(link, log_level,
                               "Reducing requested IPv6 MTU %"PRIu32" to the interface's maximum MTU %"PRIu32".",
-                              mtu, link->max_mtu);
-                mtu = link->max_mtu;
+                              mtu, link->mtu);
+                mtu = link->mtu;
         }
 
         r = sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "mtu", mtu, manager_get_sysctl_shadow(link->manager));
diff --git a/test/test-network/systemd-networkd-tests.py b/test/test-network/systemd-networkd-tests.py
index 8609a63916..8775c49ec8 100755
--- a/test/test-network/systemd-networkd-tests.py
+++ b/test/test-network/systemd-networkd-tests.py
@@ -7592,15 +7592,36 @@ class NetworkdRATests(unittest.TestCase, Utilities):
             timeout_sec=10,
         )
 
+        print('### before sending NA without router flag')
+        output = check_output('ip -6 route show dev veth99')
+        print(output)
+        self.assertIn('2002:da8:1::/64 proto ra', output)
+        self.assertIn('2002:da8:2::/64 proto ra', output)
+        self.assertRegex(output, 'default .* proto ra')
+        self.assertRegex(output, '2002:da8:1:1:1a:2b:3c:4d .* proto redirect')
+        self.assertRegex(output, '2002:da8:1:2:1a:2b:3c:4d .* proto redirect')
+        self.assertIn('2002:da8:1:3:1a:2b:3c:4d proto redirect', output)
+
         # Send Neighbor Advertisement without the router flag to announce the default router is not available
         # anymore. Then, verify that all redirect routes and the default route are dropped.
         output = check_output('ip -6 address show dev veth-peer scope link')
         veth_peer_ipv6ll = re.search('fe80:[:0-9a-f]*', output).group()
         print(f'veth-peer IPv6LL address: {veth_peer_ipv6ll}')
         check_output(f'{test_ndisc_send} --interface veth-peer --type neighbor-advertisement --target-address {veth_peer_ipv6ll} --is-router no')  # fmt: skip
-        self.wait_route_dropped('veth99', 'proto ra', ipv='-6', timeout_sec=10)
+        self.wait_route_dropped('veth99', 'default .* proto ra', ipv='-6', timeout_sec=10)
         self.wait_route_dropped('veth99', 'proto redirect', ipv='-6', timeout_sec=10)
 
+        # Check if the non-default routes are unchanged, and others are actually dropped.
+        print('### after sending NA without router flag')
+        output = check_output('ip -6 route show dev veth99')
+        print(output)
+        self.assertIn('2002:da8:1::/64 proto ra', output)
+        self.assertIn('2002:da8:2::/64 proto ra', output)
+        self.assertNotRegex(output, 'default .* proto ra')
+        self.assertNotRegex(output, '2002:da8:1:1:1a:2b:3c:4d .* proto redirect')
+        self.assertNotRegex(output, '2002:da8:1:2:1a:2b:3c:4d .* proto redirect')
+        self.assertNotIn('2002:da8:1:3:1a:2b:3c:4d proto redirect', output)
+
         # Check if sd-radv refuses RS from the same interface.
         # See https://github.com/systemd/systemd/pull/32267#discussion_r1566721306
         since = datetime.datetime.now()
@@ -11096,7 +11117,7 @@ if __name__ == '__main__':
     if build_dir:
         test_ndisc_send = os.path.normpath(os.path.join(build_dir, 'test-ndisc-send'))
     else:
-        test_ndisc_send = '/usr/lib/tests/test-ndisc-send'
+        test_ndisc_send = '/usr/lib/systemd/tests/unit-tests/manual/test-ndisc-send'
 
     if build_dir:
         test_modem_manager_mock = os.path.normpath(os.path.join(build_dir, 'test-modem-manager-mock'))