diff --git a/packages/ns-api/files/ns.threatshield b/packages/ns-api/files/ns.threatshield
index fa061d7d0..e25d718b9 100644
--- a/packages/ns-api/files/ns.threatshield
+++ b/packages/ns-api/files/ns.threatshield
@@ -736,12 +736,29 @@ def dns_list_zones(e_uci):
         zones.append(zone['name'])
     return { 'data': zones }
 
+def dns_zones_to_devices(e_uci, zones):
+    # adb_nftdevforce is rendered as an nft iifname match, so it needs the devices
+    # of the selected zones and not the zone names
+    devices = set()
+    for zone in zones:
+        devices.update(utils.get_all_devices_by_zone(e_uci, zone, exclude_aliases=True))
+    return sorted(devices)
+
+def dns_set_enforced_devices(e_uci, zones):
+    devices = dns_zones_to_devices(e_uci, zones)
+    if devices:
+        e_uci.set('adblock', 'global', 'adb_nftdevforce', devices)
+    elif e_uci.get('adblock', 'global', 'adb_nftdevforce', list=True, default=[]):
+        # no device in the selected zones: adblock skips the enforcement altogether
+        e_uci.delete('adblock', 'global', 'adb_nftdevforce')
+
 def dns_list_settings(e_uci):
     ts_enabled = e_uci.get('adblock', 'global', 'ts_enabled', default='0')
-    try:
-        zones = list(e_uci.get_all('adblock', 'global', 'adb_nftdevforce'))
-    except:
-        zones = ['lan']
+    # the user selection is stored in ns_tsdns_zones: adb_nftdevforce holds the devices
+    # derived from it and can't be mapped back to zones without ambiguity. Installations
+    # predating the device-based enforcement are converted by 96_ns-threat_shield, so the
+    # option is always set at this point
+    zones = list(e_uci.get('adblock', 'global', 'ns_tsdns_zones', list=True, default=['lan']))
     try:
         ports = list(e_uci.get_all('adblock', 'global', 'adb_nftportforce'))
     except:
@@ -750,13 +767,15 @@ def dns_list_settings(e_uci):
 
 def dns_edit_settings(e_uci, payload):
     if payload['enabled']:
-        if 'zones' in payload and 'wan' in payload['zones']:
-            raise ValidationError('zones', 'wan_zone_not_allowed', payload['zones'])
+        zones = payload.get('zones', ['lan'])
+        if 'wan' in zones:
+            raise ValidationError('zones', 'wan_zone_not_allowed', zones)
         e_uci.set('adblock', 'global', 'ts_enabled', '1')
         e_uci.set('adblock', 'global', 'adb_enabled', '1')
         e_uci.set('adblock', 'global', 'adb_triggerdelay', '30')
         e_uci.set('adblock', 'global', 'adb_nftforce', '1')
-        e_uci.set('adblock', 'global', 'adb_nftdevforce', payload.get('zones', ['lan']))
+        e_uci.set('adblock', 'global', 'ns_tsdns_zones', zones)
+        dns_set_enforced_devices(e_uci, zones)
         e_uci.set('adblock', 'global', 'adb_nftportforce', payload.get('ports', ['53', '853']))
     else:
         e_uci.set('adblock', 'global', 'ts_enabled', '0')
diff --git a/packages/ns-threat_shield/Makefile b/packages/ns-threat_shield/Makefile
index f077c9d00..7a465ab7e 100644
--- a/packages/ns-threat_shield/Makefile
+++ b/packages/ns-threat_shield/Makefile
@@ -43,6 +43,7 @@ define Package/ns-threat_shield/install
 	$(INSTALL_DIR) $(1)/usr/share/ns-plug/hooks/unregister
 	$(INSTALL_DIR) $(1)/usr/libexec/ns-api/post-commit
 	$(INSTALL_DIR) $(1)/usr/libexec/ns-api/pre-commit
+	$(INSTALL_DIR) $(1)/usr/libexec
 	$(INSTALL_BIN) ./files/ts-dns $(1)/usr/sbin/ts-dns
 	$(INSTALL_BIN) ./files/ts-ip $(1)/usr/sbin/ts-ip
 	$(INSTALL_BIN) ./files/20_threat_shield $(1)/etc/uci-defaults
@@ -56,9 +57,12 @@ define Package/ns-threat_shield/install
 	$(INSTALL_DATA) ./files/banip.nethesis.feeds $(1)/etc/banip
 	$(INSTALL_BIN) ./files/adjust-banip.py $(1)/usr/libexec/ns-api/post-commit/
 	$(INSTALL_BIN) ./files/configure-banip-wans.py $(1)/usr/libexec/ns-api/pre-commit/
+	$(INSTALL_BIN) ./files/configure-adblock-devices.py $(1)/usr/libexec/ns-api/pre-commit/
+	$(INSTALL_BIN) ./files/adblock-devices-migrate.py $(1)/usr/libexec/ts-dns-migrate-devices
 	$(INSTALL_DIR) $(1)/etc/uci-defaults
 	$(INSTALL_BIN) ./files/banip-defaults $(1)/etc/uci-defaults/99-nethsec-banip
 	$(INSTALL_BIN) ./files/35_ns-threat_shield $(1)/etc/uci-defaults/35_ns-threat_shield
+	$(INSTALL_BIN) ./files/96_ns-threat_shield $(1)/etc/uci-defaults/96_ns-threat_shield
 	gzip -9n $(1)/usr/share/threat_shield/nethesis-dns.sources
 	gzip -9n $(1)/usr/share/threat_shield/community-dns.sources
 endef
diff --git a/packages/ns-threat_shield/README.md b/packages/ns-threat_shield/README.md
index 6943b0ebc..1773bbd5f 100644
--- a/packages/ns-threat_shield/README.md
+++ b/packages/ns-threat_shield/README.md
@@ -52,9 +52,16 @@ ts-ip
 Threat shield DNS (`ts-dns`) is a special configuration for [adblock](https://github.com/openwrt/packages/tree/master/net/adblock).
 The `ts-dns` is invoked every time adblock is started or reloaded.
 
-The package adds a new option to `adblock`:
+The package adds new options to `adblock`:
 
 - `ts_enabled`: if set to `1`, it enables the download of enterprise categories and community free categories.
+- `ns_tsdns_zones`: the firewall zones where the local DNS enforcement is applied.
+
+Since adblock 4.5.5 the enforcement is rendered as nft rules matching on `iifname`, so the
+`adb_nftdevforce` option needs network devices and not zone names. It is therefore a derived
+value: it is computed from `ns_tsdns_zones` by the API and kept aligned with the network setup
+by the `configure-adblock-devices` pre-commit hook, so that adding an interface to an enforced
+zone does not leave its DNS traffic unfiltered. Do not edit `adb_nftdevforce` by hand.
 
 If `ts_enabled` is set to 1:
 
diff --git a/packages/ns-threat_shield/files/96_ns-threat_shield b/packages/ns-threat_shield/files/96_ns-threat_shield
new file mode 100644
index 000000000..c2b56406f
--- /dev/null
+++ b/packages/ns-threat_shield/files/96_ns-threat_shield
@@ -0,0 +1,17 @@
+#!/bin/sh
+
+#
+# Copyright (C) 2026 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+# Rebuild the adblock local DNS enforcement on systems upgraded from adblock 4.1.5,
+# where adb_nftdevforce ended up holding firewall zone names instead of devices.
+#
+# This must run after 95-adblock-housekeeping: on systems coming from adblock 4.1.5
+# the selection still lives in adb_zonelist, and it is that script which copies it
+# into adb_nftdevforce
+
+set -e
+
+/usr/libexec/ts-dns-migrate-devices
diff --git a/packages/ns-threat_shield/files/adblock-devices-migrate.py b/packages/ns-threat_shield/files/adblock-devices-migrate.py
new file mode 100644
index 000000000..0a5ca8fbe
--- /dev/null
+++ b/packages/ns-threat_shield/files/adblock-devices-migrate.py
@@ -0,0 +1,58 @@
+#!/usr/bin/env python
+
+#
+# Copyright (C) 2026 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+# this script is supposed to be run by the 96_ns-threat_shield uci defaults
+#
+# Up to adblock 4.1.5 the local DNS enforcement was configured through adb_zonelist,
+# holding firewall zone names, and adblock turned it into uci redirect sections
+# letting fw4 resolve the zones. Since 4.5.5 the enforcement is rendered as nft rules
+# matching on iifname, so adb_nftdevforce needs device names: the zone names stored
+# there produce rules that never match and DNS traffic is no longer redirected.
+#
+# Move the selection to ns_tsdns_zones and rebuild adb_nftdevforce out of it.
+
+import subprocess
+
+from euci import EUci
+from nethsec import firewall, utils
+
+
+def migrate_zones():
+    e_uci = EUci()
+
+    if list(e_uci.get('adblock', 'global', 'ns_tsdns_zones', list=True, default=[])):
+        # already migrated
+        return False
+
+    zones = list(e_uci.get('adblock', 'global', 'adb_nftdevforce', list=True, default=[]))
+    if not zones:
+        return False
+
+    if not all(firewall.zone_exists(e_uci, zone) for zone in zones):
+        # the stored values are device names already, or zones that no longer exist:
+        # they can't be mapped back to a selection, leave the configuration untouched
+        return False
+
+    devices = set()
+    for zone in zones:
+        devices.update(utils.get_all_devices_by_zone(e_uci, zone, exclude_aliases=True))
+
+    # record the selection even when it yields no device, so the API keeps reporting
+    # the zones the user picked instead of falling back to the default one
+    e_uci.set('adblock', 'global', 'ns_tsdns_zones', zones)
+    if devices:
+        e_uci.set('adblock', 'global', 'adb_nftdevforce', sorted(devices))
+    else:
+        # no device in the selected zones: adblock skips the enforcement altogether
+        e_uci.delete('adblock', 'global', 'adb_nftdevforce')
+    e_uci.commit('adblock')
+    return True
+
+
+if __name__ == "__main__":
+    if migrate_zones():
+        subprocess.run(["/etc/init.d/adblock", "restart"], capture_output=True)
diff --git a/packages/ns-threat_shield/files/configure-adblock-devices.py b/packages/ns-threat_shield/files/configure-adblock-devices.py
new file mode 100755
index 000000000..7515f8dd7
--- /dev/null
+++ b/packages/ns-threat_shield/files/configure-adblock-devices.py
@@ -0,0 +1,38 @@
+#!/usr/bin/python
+
+#
+# Copyright (C) 2026 Nethesis S.r.l.
+# SPDX-License-Identifier: GPL-2.0-only
+#
+
+# This script keeps the adblock local DNS enforcement aligned with the network setup:
+# adb_nftdevforce is rendered as an nft iifname match, so it must list the devices of
+# the zones selected in ns_tsdns_zones. Without this, adding an interface to an
+# enforced zone would silently leave its DNS traffic unfiltered.
+
+# The changes variable is already within the scope from the caller
+if 'adblock' in changes or 'firewall' in changes or 'network' in changes:
+    import syslog
+    from euci import EUci
+    from nethsec import utils
+
+    uci = EUci()
+    zones = list(uci.get('adblock', 'global', 'ns_tsdns_zones', list=True, default=[]))
+
+    if zones:
+        devices = set()
+        for zone in zones:
+            devices.update(utils.get_all_devices_by_zone(uci, zone, exclude_aliases=True))
+        # keep a stable order, the value is compared before being rewritten
+        devices = sorted(devices)
+
+        current = list(uci.get('adblock', 'global', 'adb_nftdevforce', list=True, default=[]))
+        if devices != current:
+            if devices:
+                uci.set('adblock', 'global', 'adb_nftdevforce', devices)
+            else:
+                uci.delete('adblock', 'global', 'adb_nftdevforce')
+            uci.save('adblock')
+            # adblock is reloaded by the uci reload_config at the end of the commit
+            if 'adblock' not in changes:
+                changes['adblock'] = {}