diff --git a/data/templates/ipsec/swanctl/l2tp.j2 b/data/templates/ipsec/swanctl/l2tp.j2
index 7eaf9087de4..da3ff40d526 100644
--- a/data/templates/ipsec/swanctl/l2tp.j2
+++ b/data/templates/ipsec/swanctl/l2tp.j2
@@ -2,7 +2,7 @@
 {% set l2tp_ike = ike_group[l2tp.ike_group] if l2tp.ike_group is vyos_defined else None %}
 {% set l2tp_esp = esp_group[l2tp.esp_group] if l2tp.esp_group is vyos_defined else None %}
     l2tp_remote_access {
-        proposals = {{ l2tp_ike | get_esp_ike_cipher | join(',') if l2tp_ike else l2tp_ike_default }}
+        proposals = {{ l2tp_ike | get_esp_ike_cipher(esn=False) | join(',') if l2tp_ike else l2tp_ike_default }}
         local_addrs = {{ l2tp_outside_address }}
         dpd_delay = 15s
         dpd_timeout = 45s
diff --git a/data/templates/ipsec/swanctl/peer.j2 b/data/templates/ipsec/swanctl/peer.j2
index 96f761ccee5..ee2efcc508b 100644
--- a/data/templates/ipsec/swanctl/peer.j2
+++ b/data/templates/ipsec/swanctl/peer.j2
@@ -19,7 +19,7 @@
 {% if peer_conf.childless is vyos_defined %}
         childless = {{ peer_conf.childless }}
 {% endif %}
-        proposals = {{ ike | get_esp_ike_cipher | join(',') }}
+        proposals = {{ ike | get_esp_ike_cipher(esn=False) | join(',') }}
         version = {{ ike.key_exchange[4:] if ike.key_exchange is vyos_defined else "0" }}
 {% if peer_conf.virtual_address is vyos_defined %}
         vips = {{ peer_conf.virtual_address | join(', ') }}
diff --git a/data/templates/ipsec/swanctl/profile.j2 b/data/templates/ipsec/swanctl/profile.j2
index 10fe0a8eca3..1aec635fd3d 100644
--- a/data/templates/ipsec/swanctl/profile.j2
+++ b/data/templates/ipsec/swanctl/profile.j2
@@ -5,7 +5,7 @@
 {% if profile_conf.bind.tunnel is vyos_defined %}
 {%     for interface in profile_conf.bind.tunnel %}
     dmvpn-{{ name }}-{{ interface }} {
-        proposals = {{ ike_group[profile_conf.ike_group] | get_esp_ike_cipher | join(',') }}
+        proposals = {{ ike_group[profile_conf.ike_group] | get_esp_ike_cipher(esn=False) | join(',') }}
         version = {{ ike.key_exchange[4:] if ike.key_exchange is vyos_defined else "0" }}
         rekey_time = {{ ike.lifetime }}s
         keyingtries = 0
diff --git a/data/templates/ipsec/swanctl/remote_access.j2 b/data/templates/ipsec/swanctl/remote_access.j2
index 639248caf8f..7d89ced8b03 100644
--- a/data/templates/ipsec/swanctl/remote_access.j2
+++ b/data/templates/ipsec/swanctl/remote_access.j2
@@ -14,7 +14,7 @@
 {% endif %}
         remote_addrs = %any
         local_addrs = {{ rw_conf.local_address if rw_conf.local_address is not vyos_defined('any') else '%any' }} # dhcp:{{ rw_conf.dhcp_interface if rw_conf.dhcp_interface is vyos_defined else 'no' }}
-        proposals = {{ ike_group[rw_conf.ike_group] | get_esp_ike_cipher | join(',') }}
+        proposals = {{ ike_group[rw_conf.ike_group] | get_esp_ike_cipher(esn=False) | join(',') }}
         version = {{ ike.key_exchange[4:] if ike.key_exchange is vyos_defined else "0" }}
         send_certreq = no
 {% if rw_conf.authentication.always_send_cert is vyos_defined %}
diff --git a/python/vyos/template.py b/python/vyos/template.py
index 5b228603cf5..8c83821416f 100755
--- a/python/vyos/template.py
+++ b/python/vyos/template.py
@@ -483,7 +483,16 @@ def get_first_ike_dh_group(ike_group):
     return 'dh-group2' # Fallback on dh-group2
 
 @register_filter('get_esp_ike_cipher')
-def get_esp_ike_cipher(group_config, ike_group=None):
+def get_esp_ike_cipher(group_config, ike_group=None, esn=True):
+    """Render strongSwan proposal strings.
+
+    esn=True  : ESP/CHILD_SA proposals, where ESN transforms are meaningful
+    esn=False : IKE_SA proposals. ESN is a CHILD_SA transform (RFC 7296
+                section 3.3.2, Transform Type 5) and has no meaning in an
+                IKE_SA proposal. Emitting it there breaks interoperability
+                with implementations that reject the malformed payload
+                without replying at all (observed with Cisco FTD, T9254).
+    """
     pfs_lut = {
         'dh-group1'  : 'modp768',
         'dh-group2'  : 'modp1024',
@@ -533,7 +542,7 @@ def get_esp_ike_cipher(group_config, ike_group=None):
             # For 'optional' and 'disabled' we need two values as
             # proposal without '-esn'/'-noesn' is incompatible with
             # proposals with any of them.
-            if 'esn' in proposal:
+            if esn and 'esn' in proposal:
                 if proposal['esn'] == 'required':
                     tmp += '-esn'
                 elif proposal['esn'] == 'optional':
diff --git a/smoketest/scripts/cli/test_vpn_ipsec.py b/smoketest/scripts/cli/test_vpn_ipsec.py
index a73cd0b2bcb..252e881df85 100755
--- a/smoketest/scripts/cli/test_vpn_ipsec.py
+++ b/smoketest/scripts/cli/test_vpn_ipsec.py
@@ -252,7 +252,7 @@ def test_site_to_site(self):
             f'life_bytes = {life_bytes}',
             f'life_packets = {life_packets}',
             f'rekey_time = 28800s', # default value
-            f'proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
+            f'proposals = aes128-sha1-modp1024',
             f'esp_proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
             f'life_time = 3600s', # default value
             f'local_addrs = {local_address} # dhcp:no',
@@ -406,7 +406,7 @@ def test_site_to_site_with_default_ts(self):
             f'life_bytes = {life_bytes}',
             f'life_packets = {life_packets}',
             f'rekey_time = 28800s',  # default value
-            f'proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
+            f'proposals = aes128-sha1-modp1024',
             f'esp_proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
             f'life_time = 3600s',  # default value
             f'local_addrs = {local_address} # dhcp:no',
@@ -482,7 +482,7 @@ def test_site_to_site_gre_over_ipsec(self):
         swanctl_conf_lines = [
             'version = 2',
             'auth = psk',
-            'proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024,aes256-sha1-modp1536-noesn,aes256-sha1-modp1536',
+            'proposals = aes128-sha1-modp1024,aes256-sha1-modp1536',
             'esp_proposals = aes128-sha1-modp2048-noesn,aes128-sha1-modp2048,aes256-sha1-modp2048-noesn,aes256-sha1-modp2048',
             'life_time = 3600s',
             'mode = transport',  # ensure transport mode is used
@@ -549,7 +549,7 @@ def test_site_to_site_vti(self):
         swanctl_conf_lines = [
             f'version = 2',
             f'auth = psk',
-            f'proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
+            f'proposals = aes128-sha1-modp1024',
             f'esp_proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
             f'local_addrs = {local_address} # dhcp:no',
             f'mobike = no',
@@ -625,7 +625,7 @@ def test_site_to_site_vti_ts_afi(self):
         swanctl_conf_lines = [
             f'version = 2',
             f'auth = psk',
-            f'proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
+            f'proposals = aes128-sha1-modp1024',
             f'esp_proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
             f'local_addrs = {local_address} # dhcp:no',
             f'mobike = no',
@@ -765,7 +765,7 @@ def test_site_to_site_nist_800_77_cnsa_1_with_ppk(self):
             f'version = 2',
             f'auth = psk',
             f'rekey_time = 86400s',
-            f'proposals = aes256gcm128-sha384-prfsha384-ecp384-noesn,aes256gcm128-sha384-prfsha384-ecp384',
+            f'proposals = aes256gcm128-sha384-prfsha384-ecp384',
             f'esp_proposals = aes256gcm128-sha384-ecp384-noesn,aes256gcm128-sha384-ecp384',
             f'life_time = 28800s',  # default value
             f'local_addrs = {local_address} # dhcp:no',
@@ -869,7 +869,7 @@ def test_dmvpn(self):
 
         swanctl_conf = read_file(swanctl_file)
         swanctl_lines = [
-            f'proposals = aes256-sha1-prfsha1-modp1024-noesn,aes256-sha1-prfsha1-modp1024',
+            f'proposals = aes256-sha1-prfsha1-modp1024',
             f'version = 1',
             f'rekey_time = {ike_lifetime}s',
             f'rekey_time = {esp_lifetime}s',
@@ -932,7 +932,7 @@ def test_site_to_site_x509(self):
             f'id = "{peer_name}"',
             f'auth = pubkey',
             f'certs = {peer_name}.pem',
-            f'proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
+            f'proposals = aes128-sha1-modp1024',
             f'esp_proposals = aes128-sha1-modp1024-noesn,aes128-sha1-modp1024',
             f'local_addrs = {local_address} # dhcp:no',
             f'remote_addrs = {peer_ip}',
@@ -1188,7 +1188,7 @@ def test_remote_access(self):
             f'{conn_name}',
             f'remote_addrs = %any',
             f'local_addrs = {local_address}',
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048,aes256-sha256-modp2048-noesn,aes256-sha256-modp2048,aes256-sha256-modp1024-noesn,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048-noesn,aes128gcm128-sha256-modp2048',
+            f'proposals = aes256-sha512-modp2048,aes256-sha256-modp2048,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048',
             f'version = 2',
             f'send_certreq = no',
             f'rekey_time = {ike_lifetime}s',
@@ -1308,7 +1308,7 @@ def test_remote_access_eap_tls(self):
             f'{conn_name}',
             f'remote_addrs = %any',
             f'local_addrs = {local_address}',
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048,aes256-sha256-modp2048-noesn,aes256-sha256-modp2048,aes256-sha256-modp1024-noesn,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048-noesn,aes128gcm128-sha256-modp2048',
+            f'proposals = aes256-sha512-modp2048,aes256-sha256-modp2048,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048',
             f'version = 2',
             f'send_certreq = no',
             f'rekey_time = {ike_lifetime}s',
@@ -1424,7 +1424,7 @@ def test_remote_access_x509(self):
             f'{conn_name}',
             f'remote_addrs = %any',
             f'local_addrs = {local_address}',
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048,aes256-sha256-modp2048-noesn,aes256-sha256-modp2048,aes256-sha256-modp1024-noesn,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048-noesn,aes128gcm128-sha256-modp2048',
+            f'proposals = aes256-sha512-modp2048,aes256-sha256-modp2048,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048',
             f'version = 2',
             f'send_certreq = no',
             f'rekey_time = {ike_lifetime}s',
@@ -1622,7 +1622,7 @@ def test_remote_access_no_rekey(self):
             f'{conn_name}',
             f'remote_addrs = %any',
             f'local_addrs = {local_address}',
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048,aes256-sha256-modp2048-noesn,aes256-sha256-modp2048,aes256-sha256-modp1024-noesn,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048-noesn,aes128gcm128-sha256-modp2048',
+            f'proposals = aes256-sha512-modp2048,aes256-sha256-modp2048,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048',
             f'version = 2',
             f'send_certreq = no',
             f'rekey_time = 0s',
@@ -1735,7 +1735,7 @@ def test_remote_access_pool_range(self):
             f'{conn_name}',
             f'remote_addrs = %any',
             f'local_addrs = {local_address}',
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048,aes256-sha256-modp2048-noesn,aes256-sha256-modp2048,aes256-sha256-modp1024-noesn,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048-noesn,aes128gcm128-sha256-modp2048',
+            f'proposals = aes256-sha512-modp2048,aes256-sha256-modp2048,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048',
             f'version = 2',
             f'send_certreq = no',
             f'rekey_time = {ike_lifetime}s',
@@ -1868,7 +1868,7 @@ def test_remote_access_vti(self):
             f'{conn_name}',
             f'remote_addrs = %any',
             f'local_addrs = {local_address}',
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048,aes256-sha256-modp2048-noesn,aes256-sha256-modp2048,aes256-sha256-modp1024-noesn,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048-noesn,aes128gcm128-sha256-modp2048',
+            f'proposals = aes256-sha512-modp2048,aes256-sha256-modp2048,aes256-sha256-modp1024,aes128gcm128-sha256-modp2048',
             f'version = 2',
             f'send_certreq = no',
             f'rekey_time = {ike_lifetime}s',
@@ -2010,7 +2010,7 @@ def test_esn_settings(self):
         # esn - default, disabled
         swanctl_conf = read_file(swanctl_file)
         swanctl_conf_lines = [
-            f'proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048',
+            f'proposals = aes256-sha512-modp2048',
             f'esp_proposals = aes256-sha512-modp2048-noesn,aes256-sha512-modp2048',
         ]
         for line in swanctl_conf_lines:
@@ -2023,7 +2023,7 @@ def test_esn_settings(self):
 
         swanctl_conf = read_file(swanctl_file)
         swanctl_conf_lines = [
-            f'proposals = aes256-sha512-modp2048-esn-noesn,aes256-sha512-modp2048',
+            f'proposals = aes256-sha512-modp2048',
             f'esp_proposals = aes256-sha512-modp2048-esn-noesn,aes256-sha512-modp2048',
         ]
         for line in swanctl_conf_lines:
@@ -2036,7 +2036,7 @@ def test_esn_settings(self):
 
         swanctl_conf = read_file(swanctl_file)
         swanctl_conf_lines = [
-            f'proposals = aes256-sha512-modp2048-esn',
+            f'proposals = aes256-sha512-modp2048',
             f'esp_proposals = aes256-sha512-modp2048-esn',
         ]
         for line in swanctl_conf_lines: