diff --git a/components/aes67_net/aes67_net.c b/components/aes67_net/aes67_net.c
index ba95825..695a7ae 100644
--- a/components/aes67_net/aes67_net.c
+++ b/components/aes67_net/aes67_net.c
@@ -11,10 +11,13 @@
 #include "esp_log.h"
 #include "esp_netif.h"
 #include "lldp.h"
+#include "lwip/inet.h"
 #include "mdns.h"
 
 static const char *TAG = "net";
 
+static const char *const ADDR_KEYS[] = { "dhcp", "ip", "mask", "gw", "dns" };
+
 // AES67 / untagged interface.
 static const char NET_DEFAULTS[] =
     "{\"hostname\":\"aes67\",\"vlan\":false,\"web_on\":\"both\",\"dhcp\":true,"
@@ -25,6 +28,48 @@ static const char INET_DEFAULTS[] =
 
 static esp_netif_t *s_netif;
 static char s_link[24] = "down";
+static cJSON *s_addr;               // addressing in use since boot (ADDR_KEYS of "net")
+
+// The keys that define the IP setup. With DHCP the static fields don't matter (the UI fills them
+// with the lease), so they don't count as a change.
+static cJSON *addressing(const cJSON *g)
+{
+    cJSON *a = cJSON_CreateObject();
+    int n = cJSON_IsTrue(cJSON_GetObjectItemCaseSensitive(g, "dhcp")) ? 1 : sizeof(ADDR_KEYS) / sizeof(ADDR_KEYS[0]);
+    for (int i = 0; i < n; i++) {
+        cJSON_AddItemToObject(a, ADDR_KEYS[i], cJSON_Duplicate(cJSON_GetObjectItemCaseSensitive(g, ADDR_KEYS[i]), true));
+    }
+    return a;
+}
+
+static uint32_t addr_of(const cJSON *g, const char *key)
+{
+    const cJSON *v = cJSON_GetObjectItemCaseSensitive(g, key);
+    return cJSON_IsString(v) && v->valuestring[0] ? inet_addr(v->valuestring) : 0;
+}
+
+// Static addressing: stop the DHCP client and set ours. On link up, like IDF's static IP example.
+static void set_static(void)
+{
+    if (cJSON_IsTrue(cJSON_GetObjectItemCaseSensitive(s_addr, "dhcp"))) {
+        return;
+    }
+    esp_err_t err = esp_netif_dhcpc_stop(s_netif);
+    if (err != ESP_OK && err != ESP_ERR_ESP_NETIF_DHCP_ALREADY_STOPPED) {
+        ESP_LOGE(TAG, "DHCP client stop: %s", esp_err_to_name(err));
+    }
+    esp_netif_ip_info_t ip = {
+        .ip.addr = addr_of(s_addr, "ip"), .netmask.addr = addr_of(s_addr, "mask"), .gw.addr = addr_of(s_addr, "gw"),
+    };
+    err = esp_netif_set_ip_info(s_netif, &ip);
+    if (err != ESP_OK) {
+        ESP_LOGE(TAG, "static IP: %s", esp_err_to_name(err));
+    }
+    esp_netif_dns_info_t dns = { .ip.type = ESP_IPADDR_TYPE_V4, .ip.u_addr.ip4.addr = addr_of(s_addr, "dns") };
+    if (dns.ip.u_addr.ip4.addr) {
+        esp_netif_set_dns_info(s_netif, ESP_NETIF_DNS_MAIN, &dns);
+    }
+}
 
 static void eth_event(void *arg, esp_event_base_t base, int32_t id, void *data)
 {
@@ -43,6 +88,7 @@ static void eth_event(void *arg, esp_event_base_t base, int32_t id, void *data)
                  mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
         snprintf(s_link, sizeof(s_link), "up, %s Mbps %s", speed == ETH_SPEED_100M ? "100" : "10",
                  duplex == ETH_DUPLEX_FULL ? "full" : "half");
+        set_static();
         break;
     }
     case ETHERNET_EVENT_DISCONNECTED:
@@ -66,10 +112,27 @@ static void ip_event(void *arg, esp_event_base_t base, int32_t id, void *data)
 static bool check_addr(const cJSON *g, char *err, size_t n)
 {
     bool dhcp = cJSON_IsTrue(cJSON_GetObjectItemCaseSensitive(g, "dhcp"));
-    return cfg_check_ipv4(g, "ip", dhcp, err, n) &&
-           cfg_check_ipv4(g, "mask", dhcp, err, n) &&
-           cfg_check_ipv4(g, "gw", true, err, n) &&
-           cfg_check_ipv4(g, "dns", true, err, n);
+    if (!cfg_check_ipv4(g, "ip", dhcp, err, n) || !cfg_check_ipv4(g, "mask", dhcp, err, n) ||
+        !cfg_check_ipv4(g, "gw", true, err, n) || !cfg_check_ipv4(g, "dns", true, err, n)) {
+        return false;
+    }
+    if (dhcp) {
+        return true;
+    }
+    uint32_t ip = ntohl(addr_of(g, "ip")), mask = ntohl(addr_of(g, "mask")), gw = ntohl(addr_of(g, "gw"));
+    if (mask == 0 || (~mask & (~mask + 1)) != 0 || mask == 0xffffffff) {
+        snprintf(err, n, "mask: not a valid netmask");
+        return false;
+    }
+    if ((ip & ~mask) == 0 || (ip & ~mask) == ~mask) {
+        snprintf(err, n, "ip: network or broadcast address of the subnet");
+        return false;
+    }
+    if (gw && ((gw & mask) != (ip & mask) || gw == ip)) {
+        snprintf(err, n, "gw: must be another address in the IP's subnet");
+        return false;
+    }
+    return true;
 }
 
 // RFC 1123 label: letters, digits, hyphen; not starting or ending with a hyphen.
@@ -134,6 +197,13 @@ static void net_apply(const cJSON *g)
         ESP_LOGI(TAG, "mDNS: now %s.local", host);
     }
     lldp_changed();
+    // New addressing: PTP/TX/SAP sockets are bound to the address, so it takes a reboot.
+    cJSON *a = addressing(g);
+    if (!cJSON_Compare(a, s_addr, true)) {
+        ESP_LOGW(TAG, "IP setup changed: rebooting to apply it");
+        web_reboot_later(1500);
+    }
+    cJSON_Delete(a);
 }
 
 static void net_status(cJSON *st)
@@ -169,7 +239,7 @@ static void net_status(cJSON *st)
 
 esp_err_t aes67_net_init(esp_eth_handle_t eth)
 {
-    // Applied so far: hostname (DHCP, mDNS, LLDP). Static IP and VLAN come later.
+    // Applied: hostname (DHCP, mDNS, LLDP) live; DHCP/static addressing at boot. VLAN comes later.
     ESP_ERROR_CHECK(cfg_register("net", NET_DEFAULTS, net_validate, net_apply));
     ESP_ERROR_CHECK(cfg_register("inet", INET_DEFAULTS, inet_validate, NULL));
 
@@ -189,6 +259,13 @@ esp_err_t aes67_net_init(esp_eth_handle_t eth)
     // Hostname in DHCP requests (option 12), so the router's lease list shows it.
     cJSON *net = cfg_get("net");
     ESP_ERROR_CHECK(esp_netif_set_hostname(s_netif, cJSON_GetObjectItemCaseSensitive(net, "hostname")->valuestring));
+    s_addr = addressing(net);
+    if (!cJSON_IsTrue(cJSON_GetObjectItemCaseSensitive(net, "dhcp"))) {
+        ESP_LOGI(TAG, "static IP %s/%s gw %s dns %s", cJSON_GetObjectItemCaseSensitive(net, "ip")->valuestring,
+                 cJSON_GetObjectItemCaseSensitive(net, "mask")->valuestring,
+                 cJSON_GetObjectItemCaseSensitive(net, "gw")->valuestring,
+                 cJSON_GetObjectItemCaseSensitive(net, "dns")->valuestring);
+    }
     cJSON_Delete(net);
     mdns_setup();
     ESP_ERROR_CHECK(lldp_start(eth, s_netif));
diff --git a/web/index.html b/web/index.html
index 25546ad..64017ff 100644
--- a/web/index.html
+++ b/web/index.html
@@ -417,7 +417,15 @@ async function save(e) {
   const c = read();
   c.aes67.session_ver = (Number(cfg.aes67?.session_ver) || 0) + 1; // SDP version bump per RFC 4566
   await api('POST', '/api/config', c);
+  // A changed IP setup reboots the device: follow it to the new address.
+  const addr = n => n.dhcp ? 'dhcp' : [n.ip, n.mask, n.gw, n.dns].join('/');
+  const moved = addr(cfg.net || {}) !== addr(c.net);
   cfg = c; fill(); msg.textContent = 'Saved.';
+  if (moved) {
+    const to = c.net.dhcp ? location.host : c.net.ip;
+    msg.textContent = `Rebooting with the new IP setup. Opening http://${to}/ in 20 s.`;
+    setTimeout(() => location.href = `http://${to}/`, 20000);
+  }
 }
 
 // PTP display follows the Riedel (Bolero/Artist) status layout, IEEE 1588-2019 terms.