diff --git a/esphome/components/ethernet/__init__.py b/esphome/components/ethernet/__init__.py
index 0504ab7a1f0..eccd0a25a56 100644
--- a/esphome/components/ethernet/__init__.py
+++ b/esphome/components/ethernet/__init__.py
@@ -247,11 +247,16 @@ def _validate(config):
                     f"{config[CONF_TYPE]} PHY requires RMII interface and is only supported "
                     f"on ESP32 classic and ESP32-P4, not {variant}"
                 )
-    elif CORE.is_rp2040 and config[CONF_TYPE] not in RP2040_SPI_ETHERNET_TYPES:
-        raise cv.Invalid(
-            f"Only {', '.join(RP2040_SPI_ETHERNET_TYPES)} are supported on RP2040, "
-            f"not {config[CONF_TYPE]}"
-        )
+    elif CORE.is_rp2040:
+        if config[CONF_TYPE] not in RP2040_SPI_ETHERNET_TYPES:
+            raise cv.Invalid(
+                f"Only {', '.join(RP2040_SPI_ETHERNET_TYPES)} are supported on RP2040, "
+                f"not {config[CONF_TYPE]}"
+            )
+        if CONF_CLOCK_SPEED in config:
+            raise cv.Invalid(f"'{CONF_CLOCK_SPEED}' is not supported on RP2040")
+        if CONF_POLLING_INTERVAL in config:
+            raise cv.Invalid(f"'{CONF_POLLING_INTERVAL}' is not supported on RP2040")
     return config
 
 
diff --git a/esphome/components/ethernet/ethernet_component_rp2040.cpp b/esphome/components/ethernet/ethernet_component_rp2040.cpp
index 8fe930bdbf4..22a748ef48a 100644
--- a/esphome/components/ethernet/ethernet_component_rp2040.cpp
+++ b/esphome/components/ethernet/ethernet_component_rp2040.cpp
@@ -62,6 +62,8 @@ void EthernetComponent::setup() {
 
   if (!success) {
     ESP_LOGE(TAG, "Failed to initialize W5500 Ethernet");
+    delete this->eth_;  // NOLINT(cppcoreguidelines-owning-memory)
+    this->eth_ = nullptr;
     this->mark_failed();
     return;
   }
@@ -178,6 +180,7 @@ network::IPAddresses EthernetComponent::get_ip_addresses() {
 }
 
 network::IPAddress EthernetComponent::get_dns_address(uint8_t num) {
+  LwIPLock lock;
   const ip_addr_t *dns_ip = dns_getserver(num);
   return dns_ip;
 }
@@ -234,6 +237,7 @@ void EthernetComponent::start_connect_() {
   if (this->manual_ip_.has_value()) {
     // Static IP was already configured before begin() in setup()
     // Set DNS servers
+    LwIPLock lock;
     if (this->manual_ip_->dns1.is_set()) {
       ip_addr_t d;
       d = this->manual_ip_->dns1;
@@ -269,19 +273,25 @@ void EthernetComponent::dump_connect_params_() {
   char mac_buf[MAC_ADDRESS_PRETTY_BUFFER_SIZE];
 
   auto *netif = this->eth_->getNetIf();
-  ESP_LOGCONFIG(
-      TAG,
-      "  IP Address: %s\n"
-      "  Hostname: '%s'\n"
-      "  Subnet: %s\n"
-      "  Gateway: %s\n"
-      "  DNS1: %s\n"
-      "  DNS2: %s\n"
-      "  MAC Address: %s",
-      network::IPAddress(&netif->ip_addr).str_to(ip_buf), App.get_name().c_str(),
-      network::IPAddress(&netif->netmask).str_to(subnet_buf), network::IPAddress(&netif->gw).str_to(gateway_buf),
-      network::IPAddress(dns_getserver(0)).str_to(dns1_buf), network::IPAddress(dns_getserver(1)).str_to(dns2_buf),
-      this->get_eth_mac_address_pretty_into_buffer(mac_buf));
+  const ip_addr_t *dns_ip1;
+  const ip_addr_t *dns_ip2;
+  {
+    LwIPLock lock;
+    dns_ip1 = dns_getserver(0);
+    dns_ip2 = dns_getserver(1);
+  }
+  ESP_LOGCONFIG(TAG,
+                "  IP Address: %s\n"
+                "  Hostname: '%s'\n"
+                "  Subnet: %s\n"
+                "  Gateway: %s\n"
+                "  DNS1: %s\n"
+                "  DNS2: %s\n"
+                "  MAC Address: %s",
+                network::IPAddress(&netif->ip_addr).str_to(ip_buf), App.get_name().c_str(),
+                network::IPAddress(&netif->netmask).str_to(subnet_buf),
+                network::IPAddress(&netif->gw).str_to(gateway_buf), network::IPAddress(dns_ip1).str_to(dns1_buf),
+                network::IPAddress(dns_ip2).str_to(dns2_buf), this->get_eth_mac_address_pretty_into_buffer(mac_buf));
 }
 
 void EthernetComponent::set_clk_pin(uint8_t clk_pin) { this->clk_pin_ = clk_pin; }