AdguardTeam · Omoeba · Apr 11, 2026 · Apr 11, 2026 · Apr 12, 2026
diff --git a/AGHTechDoc.md b/AGHTechDoc.md
@@ -481,28 +481,32 @@ Response:
 	200 OK
 
 	{
-		"enabled":false,
-		"interface_name":"...",
-		"v4":{
-			"gateway_ip":"...",
-			"subnet_mask":"...",
-			"range_start":"...", // if empty: DHCPv4 won't be enabled
-			"range_end":"...",
-			"lease_duration":60,
-		},
-		"v6":{
-			"range_start":"...", // if empty: DHCPv6 won't be enabled
-			"lease_duration":60,
-		}
-		"leases":[
-			{"ip":"...","mac":"...","hostname":"...","expires":"..."}
-			...
-		],
-		"static_leases":[
-			{"ip":"...","mac":"...","hostname":"..."}
-			...
-		]
-	}
+```none
+{
+	"enabled":false,
+	"interface_name":"...",
+	"v4":{
+		"gateway_ip":"...",
+		"subnet_mask":"...",
+		"range_start":"...", // if empty: DHCPv4 won't be enabled
+		"range_end":"...",
+		"lease_duration":60,
+	},
+	"v6":{
+		"prefix_source":"static",
+		"range_start":"...", // if empty: DHCPv6 won't be enabled
+		"lease_duration":60,
+	},
+	"leases":[
+		{"ip":"...","mac":"...","hostname":"...","expires":"..."}
+		...
+	],
+	"static_leases":[
+		{"ip":"...","mac":"...","hostname":"..."}
+		...
+	]
+}
+```
 
 
 ### API: Check DHCP
@@ -557,23 +561,26 @@ If `static_ip.static` is:
 
 Request:
 
-	POST /control/dhcp/set_config
-
-	{
-	"enabled":true,
-	"interface_name":"vboxnet0",
-	"v4":{
-		"gateway_ip":"192.169.56.1",
-		"subnet_mask":"255.255.255.0",
-		"range_start":"192.169.56.100",
-		"range_end":"192.169.56.200", // Note: first 3 octets must match "range_start"
-		"lease_duration":60,
-	},
-	"v6":{
-		"range_start":"...",
-		"lease_duration":60,
-	}
-	}
+```none
+POST /control/dhcp/set_config
+
+{
+"enabled":true,
+"interface_name":"vboxnet0",
+"v4":{
+	"gateway_ip":"192.169.56.1",
+	"subnet_mask":"255.255.255.0",
+	"range_start":"192.169.56.100",
+	"range_end":"192.169.56.200", // Note: first 3 octets must match "range_start"
+	"lease_duration":60,
+},
+"v6":{
+	"prefix_source":"static",
+	"range_start":"...",
+	"lease_duration":60,
+}
+}
+```
 
 Response:
 
@@ -758,6 +765,12 @@ Configuration:
 * `ra_slaac_only:false; ra_allow_slaac:true`: use option #3.
 	Periodically send `ICMPv6.RouterAdvertisement(Flags=(Managed=true,Other=true))` packets.
 
+For IPv6 prefix tracking, `prefix_source:static` keeps the current
+legacy behavior.  `prefix_source:interface` derives the advertised
+prefix from the interface, keeps `range_start` as a host template for
+the dynamic pool, and deprecates the previous prefix with preferred
+lifetime `0` and a bounded valid lifetime when renumbering is observed.
+
 ICMPv6.RouterAdvertisement packet description:
 
 	ICMPv6:

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -24,6 +24,12 @@ NOTE: Add new changes BELOW THIS COMMENT.
 
 [go-1.26.2]: https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU
 
+### Added
+
+- Opt-in IPv6 prefix tracking for DHCPv6 and Router Advertisements.
+  When enabled, AdGuard Home derives the advertised prefix from the
+  interface and deprecates the previous prefix during renumbering.
+
 ### Changed
 
 #### Configuration changes

diff --git a/client/src/__locales/en.json b/client/src/__locales/en.json
@@ -152,8 +152,13 @@
   "dhcp_enable": "Enable DHCP server",
   "dhcp_error": "AdGuard Home could not determine if there is another active DHCP server on the network",
   "dhcp_form_gateway_input": "Gateway IP",
+  "dhcp_form_host_template_desc": "Used as the lower 64 bits of the dynamic pool when the prefix comes from the interface.",
+  "dhcp_form_host_template_input": "Host template",
   "dhcp_form_lease_input": "Lease duration",
   "dhcp_form_lease_title": "DHCP lease time (in seconds)",
+  "dhcp_form_prefix_source_interface": "Interface",
+  "dhcp_form_prefix_source_static": "Static",
+  "dhcp_form_prefix_source_title": "IPv6 prefix source",
   "dhcp_form_range_end": "Range end",
   "dhcp_form_range_start": "Range start",
   "dhcp_form_range_title": "Range of IP addresses",

diff --git a/client/src/components/Settings/Dhcp/FormDHCPv6.tsx b/client/src/components/Settings/Dhcp/FormDHCPv6.tsx
@@ -2,10 +2,15 @@ import React, { useMemo } from 'react';
 import { Controller, useFormContext } from 'react-hook-form';
 import { useTranslation } from 'react-i18next';
 
-import { UINT32_RANGE } from '../../../helpers/constants';
+import {
+    DHCP_V6_PREFIX_SOURCE_OPTIONS,
+    DHCP_V6_PREFIX_SOURCE_VALUES,
+    UINT32_RANGE,
+} from '../../../helpers/constants';
 import { validateIpv6, validateRequiredValue } from '../../../helpers/validators';
-import { DhcpFormValues } from '.';
+import { DhcpFormValues, hasMeaningfulV6Value, isInterfaceSLAACOnlyV6Config } from '.';
 import { Input } from '../../ui/Controls/Input';
+import { Select } from '../../ui/Controls/Select';
 import { toNumber } from '../../../helpers/form';
 
 type FormDHCPv6Props = {
@@ -30,16 +35,47 @@ const FormDHCPv6 = ({ processingConfig, ipv6placeholders, interfaces, onSubmit }
 
     const interfaceName = watch('interface_name');
     const isInterfaceIncludesIpv6 = interfaces?.[interfaceName]?.ipv6_addresses;
+    const prefixSource = watch('v6.prefix_source') ?? DHCP_V6_PREFIX_SOURCE_VALUES.STATIC;
+    const canConfigureV6 = Boolean(isInterfaceIncludesIpv6) || prefixSource === DHCP_V6_PREFIX_SOURCE_VALUES.INTERFACE;
 
     const formValues = watch('v6');
-    const isEmptyConfig = !Object.values(formValues || {}).some(Boolean);
+    const isInterfaceRASLAACOnly = isInterfaceSLAACOnlyV6Config(formValues);
+    const isRequiredForPool = !isInterfaceRASLAACOnly;
+    const isEmptyConfig = !hasMeaningfulV6Value(formValues);
 
     const isDisabled = useMemo(() => {
-        return isSubmitting || !isValid || processingConfig || !isInterfaceIncludesIpv6 || isEmptyConfig;
-    }, [isSubmitting, isValid, processingConfig, isInterfaceIncludesIpv6, isEmptyConfig]);
+        return isSubmitting || !isValid || processingConfig || !canConfigureV6 || isEmptyConfig;
+    }, [isSubmitting, isValid, processingConfig, canConfigureV6, isEmptyConfig]);
 
     return (
         <form onSubmit={handleSubmit(onSubmit)}>
+            <div className="row">
+                <div className="col-lg-6 form__group form__group--settings">
+                    <Controller
+                        name="v6.prefix_source"
+                        control={control}
+                        render={({ field }) => (
+                            <Select
+                                {...field}
+                                value={field.value ?? DHCP_V6_PREFIX_SOURCE_VALUES.STATIC}
+                                label={t('dhcp_form_prefix_source_title')}
+                                data-testid="v6_prefix_source"
+                                disabled={!interfaceName}>
+                                {DHCP_V6_PREFIX_SOURCE_OPTIONS.map((value) => (
+                                    <option key={value} value={value}>
+                                        {t(
+                                            value === DHCP_V6_PREFIX_SOURCE_VALUES.STATIC
+                                                ? 'dhcp_form_prefix_source_static'
+                                                : 'dhcp_form_prefix_source_interface',
+                                        )}
+                                    </option>
+                                ))}
+                            </Select>
+                        )}
+                    />
+                </div>
+            </div>
+
             <div className="row">
                 <div className="col-lg-6">
                     <div className="form__group mb-0">
@@ -53,10 +89,12 @@ const FormDHCPv6 = ({ processingConfig, ipv6placeholders, interfaces, onSubmit }
                                     name="v6.range_start"
                                     control={control}
                                     rules={{
-                                        validate: isInterfaceIncludesIpv6
+                                        validate: canConfigureV6
                                             ? {
                                                   ipv6: validateIpv6,
-                                                  required: validateRequiredValue,
+                                                  required: isRequiredForPool
+                                                      ? validateRequiredValue
+                                                      : undefined,
                                               }
                                             : undefined,
                                     }}
@@ -65,9 +103,19 @@ const FormDHCPv6 = ({ processingConfig, ipv6placeholders, interfaces, onSubmit }
                                             {...field}
                                             type="text"
                                             data-testid="v6_range_start"
+                                            label={
+                                                prefixSource === DHCP_V6_PREFIX_SOURCE_VALUES.INTERFACE
+                                                    ? t('dhcp_form_host_template_input')
+                                                    : t('dhcp_form_range_start')
+                                            }
                                             placeholder={t(ipv6placeholders.range_start)}
+                                            desc={
+                                                prefixSource === DHCP_V6_PREFIX_SOURCE_VALUES.INTERFACE
+                                                    ? t('dhcp_form_host_template_desc')
+                                                    : undefined
+                                            }
                                             error={fieldState.error?.message}
-                                            disabled={!isInterfaceIncludesIpv6}
+                                            disabled={!canConfigureV6}
                                         />
                                     )}
                                 />
@@ -100,9 +148,11 @@ const FormDHCPv6 = ({ processingConfig, ipv6placeholders, interfaces, onSubmit }
                         name="v6.lease_duration"
                         control={control}
                         rules={{
-                            validate: isInterfaceIncludesIpv6
+                            validate: canConfigureV6
                                 ? {
-                                      required: validateRequiredValue,
+                                      required: isRequiredForPool
+                                          ? validateRequiredValue
+                                          : undefined,
                                   }
                                 : undefined,
                         }}
@@ -114,7 +164,7 @@ const FormDHCPv6 = ({ processingConfig, ipv6placeholders, interfaces, onSubmit }
                                 label={t('dhcp_form_lease_title')}
                                 placeholder={t(ipv6placeholders.lease_duration)}
                                 error={fieldState.error?.message}
-                                disabled={!isInterfaceIncludesIpv6}
+                                disabled={!canConfigureV6}
                                 min={1}
                                 max={UINT32_RANGE.MAX}
                                 onChange={(e) => {

diff --git a/client/src/components/Settings/Dhcp/index.tsx b/client/src/components/Settings/Dhcp/index.tsx
@@ -5,7 +5,7 @@ import { shallowEqual, useDispatch, useSelector } from 'react-redux';
 import classNames from 'classnames';
 
 import { FormProvider, useForm } from 'react-hook-form';
-import { DHCP_DESCRIPTION_PLACEHOLDERS, STATUS_RESPONSE } from '../../../helpers/constants';
+import { DHCP_DESCRIPTION_PLACEHOLDERS, DHCP_V6_PREFIX_SOURCE_VALUES, STATUS_RESPONSE } from '../../../helpers/constants';
 
 import Leases from './Leases';
 
@@ -49,6 +49,8 @@ type IPv4FormValues = {
 }
 
 type IPv6FormValues = {
+    prefix_source?: string;
+    ra_slaac_only?: boolean;
     range_start?: string;
     range_end?: string;
     lease_duration?: number;
@@ -84,11 +86,37 @@ const DEFAULT_V4_VALUES = {
 };
 
 const DEFAULT_V6_VALUES = {
+    prefix_source: DHCP_V6_PREFIX_SOURCE_VALUES.STATIC,
+    ra_slaac_only: false,
     range_start: '',
     range_end: '',
     lease_duration: undefined,
 };
 
+export const isInterfaceSLAACOnlyV6Config = (v6Config: IPv6FormValues) =>
+    v6Config?.prefix_source === DHCP_V6_PREFIX_SOURCE_VALUES.INTERFACE && Boolean(v6Config?.ra_slaac_only);
+
+// V6_CONFIG_METADATA_KEYS are the IPv6 form fields that describe how the rest
+// of the configuration should be interpreted, rather than being DHCPv6 inputs
+// themselves.  They do not count as "meaningful" values on their own.
+const V6_CONFIG_METADATA_KEYS = new Set(['prefix_source', 'ra_slaac_only']);
+
+export const hasMeaningfulV6Value = (v6Config: IPv6FormValues) =>
+    isInterfaceSLAACOnlyV6Config(v6Config)
+    || Object.entries(v6Config || {}).some(
+        ([key, value]) => !V6_CONFIG_METADATA_KEYS.has(key) && Boolean(value),
+    );
+
+const isFilledV6Config = (v6Config: IPv6FormValues) =>
+    Object.entries(v6Config || {}).every(([key, value]) => (
+        V6_CONFIG_METADATA_KEYS.has(key)
+        || (
+            (key === 'range_start' || key === 'lease_duration')
+            && isInterfaceSLAACOnlyV6Config(v6Config)
+        )
+        || Boolean(value)
+    ));
+
 const Dhcp = () => {
     const { t } = useTranslation();
     const dispatch = useDispatch();
@@ -204,11 +232,11 @@ const Dhcp = () => {
 
     const enteredSomeV4Value = Object.values(v4).some(Boolean);
 
-    const enteredSomeV6Value = Object.values(v6).some(Boolean);
+    const enteredSomeV6Value = hasMeaningfulV6Value(v6);
     const enteredSomeValue = enteredSomeV4Value || enteredSomeV6Value || interfaceName;
 
     const getToggleDhcpButton = () => {
-        const filledConfig = interface_name && (Object.values(v4).every(Boolean) || Object.values(v6).every(Boolean));
+        const filledConfig = interface_name && (Object.values(v4).every(Boolean) || isFilledV6Config(v6));
 
         const className = classNames('btn btn-sm', {
             'btn-gray': enabled,

diff --git a/client/src/helpers/constants.ts b/client/src/helpers/constants.ts
@@ -449,6 +449,16 @@ export const DHCP_VALUES_PLACEHOLDERS = {
     },
 };
 
+export const DHCP_V6_PREFIX_SOURCE_VALUES = {
+    STATIC: 'static',
+    INTERFACE: 'interface',
+} as const;
+
+export const DHCP_V6_PREFIX_SOURCE_OPTIONS = [
+    DHCP_V6_PREFIX_SOURCE_VALUES.STATIC,
+    DHCP_V6_PREFIX_SOURCE_VALUES.INTERFACE,
+] as const;
+
 export const DHCP_DESCRIPTION_PLACEHOLDERS = {
     ipv4: {
         gateway_ip: 'dhcp_form_gateway_input',