@@ -124,7 +124,8 @@ void ETHClass::_onEthEvent(int32_t event_id, void *event_data) {
 }
 
 ETHClass::ETHClass(uint8_t eth_index)
-: _eth_handle(NULL), _eth_index(eth_index), _phy_type(ETH_PHY_MAX), _glue_handle(NULL), _mac(NULL), _phy(NULL)
+: _eth_handle(NULL), _eth_index(eth_index), _phy_type(ETH_PHY_MAX), _glue_handle(NULL), _mac(NULL), _phy(NULL), _eth_started(false), _link_speed(100),
+_full_duplex(true), _auto_negotiation(true)
 #if ETH_SPI_SUPPORTS_CUSTOM
 ,
 _spi(NULL)
@@ -351,6 +352,19 @@ bool ETHClass::begin(eth_phy_type_t type, int32_t phy_addr, int mdc, int mdio, i
 return false;
 }
 
+// auto negotiation needs to be disabled to change duplex mode and link speed
+if (!_auto_negotiation) {
+if (!_setAutoNegotiation(_auto_negotiation)) {
+return false;
+}
+if (!_setFullDuplex(_full_duplex)) {
+return false;
+}
+if (!_setLinkSpeed(_link_speed)) {
+return false;
+}
+}
+
 if (_eth_ev_instance == NULL && esp_event_handler_instance_register(ETH_EVENT, ESP_EVENT_ANY_ID, &_eth_event_cb, NULL, &_eth_ev_instance)) {
 log_e("event_handler_instance_register for ETH_EVENT Failed!");
 return false;
@@ -367,6 +381,8 @@ bool ETHClass::begin(eth_phy_type_t type, int32_t phy_addr, int mdc, int mdio, i
 return false;
 }
 
+_eth_started = true;
+
 if (!perimanSetPinBus(_pin_rmii_clock, ESP32_BUS_TYPE_ETHERNET_CLK, (void *)(this), -1, -1)) {
 goto err;
 }
@@ -788,6 +804,19 @@ bool ETHClass::beginSPI(
 return false;
 }
 
+// auto negotiation needs to be disabled to change duplex mode and link speed
+if (!_auto_negotiation) {
+if (!_setAutoNegotiation(_auto_negotiation)) {
+return false;
+}
+if (!_setFullDuplex(_full_duplex)) {
+return false;
+}
+if (!_setLinkSpeed(_link_speed)) {
+return false;
+}
+}
+
 if (_eth_ev_instance == NULL && esp_event_handler_instance_register(ETH_EVENT, ESP_EVENT_ANY_ID, &_eth_event_cb, NULL, &_eth_ev_instance)) {
 log_e("event_handler_instance_register for ETH_EVENT Failed!");
 return false;
@@ -803,6 +832,8 @@ bool ETHClass::beginSPI(
 return false;
 }
 
+_eth_started = true;
+
 // If Arduino's SPI is used, cs pin is in GPIO mode
 #if ETH_SPI_SUPPORTS_CUSTOM
 if (_spi == NULL) {
@@ -897,6 +928,9 @@ void ETHClass::end(void) {
 while (getStatusBits() & ESP_NETIF_STARTED_BIT) {
 delay(10);
 }
+
+_eth_started = false;
+
 //delete glue first
 if (_glue_handle != NULL) {
 if (esp_eth_del_netif_glue(_glue_handle) != ESP_OK) {
@@ -1010,7 +1044,7 @@ bool ETHClass::fullDuplex() const {
 return (link_duplex == ETH_DUPLEX_FULL);
 }
 
-bool ETHClass::setFullDuplex(bool on) {
+bool ETHClass::_setFullDuplex(bool on) {
 if (_eth_handle == NULL) {
 return false;
 }
@@ -1022,6 +1056,18 @@ bool ETHClass::setFullDuplex(bool on) {
 return err == ESP_OK;
 }
 
+bool ETHClass::setFullDuplex(bool on) {
+if (_eth_started) {
+log_e("This method must be called before ETH.begin()");
+return false;
+}
+if (_auto_negotiation) {
+log_w("Auto Negotiation MUST be OFF for this setting to be applied");
+}
+_full_duplex = on;
+return true;
+}
+
 bool ETHClass::autoNegotiation() const {
 if (_eth_handle == NULL) {
 return false;
@@ -1031,7 +1077,7 @@ bool ETHClass::autoNegotiation() const {
 return auto_nego;
 }
 
-bool ETHClass::setAutoNegotiation(bool on) {
+bool ETHClass::_setAutoNegotiation(bool on) {
 if (_eth_handle == NULL) {
 return false;
 }
@@ -1042,6 +1088,15 @@ bool ETHClass::setAutoNegotiation(bool on) {
 return err == ESP_OK;
 }
 
+bool ETHClass::setAutoNegotiation(bool on) {
+if (_eth_started) {
+log_e("This method must be called before ETH.begin()");
+return false;
+}
+_auto_negotiation = on;
+return true;
+}
+
 uint32_t ETHClass::phyAddr() const {
 if (_eth_handle == NULL) {
 return 0;
@@ -1060,7 +1115,7 @@ uint16_t ETHClass::linkSpeed() const {
 return (link_speed == ETH_SPEED_10M) ? 10 : 100;
 }
 
-bool ETHClass::setLinkSpeed(uint16_t speed) {
+bool ETHClass::_setLinkSpeed(uint16_t speed) {
 if (_eth_handle == NULL) {
 return false;
 }
@@ -1072,6 +1127,22 @@ bool ETHClass::setLinkSpeed(uint16_t speed) {
 return err == ESP_OK;
 }
 
+bool ETHClass::setLinkSpeed(uint16_t speed) {
+if (speed != 10 && speed != 100) {
+log_e("Ethernet currently supports only 10 or 100 Mbps link speed");
+return false;
+}
+if (_eth_started) {
+log_e("This method must be called before ETH.begin()");
+return false;
+}
+if (_auto_negotiation) {
+log_w("Auto Negotiation MUST be OFF for this setting to be applied");
+}
+_link_speed = speed;
+return true;
+}
+
 // void ETHClass::getMac(uint8_t* mac)
 // {
 // if(_eth_handle != NULL && mac != NULL){

@@ -229,6 +229,10 @@ class ETHClass : public NetworkInterface {
 esp_eth_netif_glue_handle_t _glue_handle;
 esp_eth_mac_t *_mac;
 esp_eth_phy_t *_phy;
+bool _eth_started;
+uint16_t _link_speed;
+bool _full_duplex;
+bool _auto_negotiation;
 #if ETH_SPI_SUPPORTS_CUSTOM
 SPIClass *_spi;
 char _cs_str[10];
@@ -257,6 +261,9 @@ class ETHClass : public NetworkInterface {
 #endif
 int sck, int miso, int mosi, spi_host_device_t spi_host, uint8_t spi_freq_mhz
 );
+bool _setFullDuplex(bool on);
+bool _setLinkSpeed(uint16_t speed);
+bool _setAutoNegotiation(bool on);
 
 friend class EthernetClass; // to access beginSPI
 };