From 402e8ea1cec1080496051edd1a271d7405c12885 Mon Sep 17 00:00:00 2001
From: Juraj Andrassy <juraj.andrassy@gmail.com>
Date: Tue, 5 Dec 2023 20:44:46 +0100
Subject: [PATCH] Ethernet - allow return to DHCP after begin with static IP

---
 libraries/Ethernet/src/Ethernet.cpp | 6 +++++-
 libraries/Ethernet/src/Ethernet.h   | 2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/libraries/Ethernet/src/Ethernet.cpp b/libraries/Ethernet/src/Ethernet.cpp
index 8d9c51a88..196afa01d 100644
--- a/libraries/Ethernet/src/Ethernet.cpp
+++ b/libraries/Ethernet/src/Ethernet.cpp
@@ -8,7 +8,11 @@ int arduino::EthernetClass::begin(uint8_t *mac, unsigned long timeout, unsigned
     _initializerCallback();
     if (eth_if == nullptr) return 0;
   }
+  eth_if->set_dhcp(true);
+  _begin(mac, timeout, responseTimeout);
+}
 
+int arduino::EthernetClass::_begin(uint8_t *mac, unsigned long timeout, unsigned long responseTimeout) {
   if (mac != nullptr) {
     eth_if->get_emac().set_hwaddr(mac);
   }
@@ -53,7 +57,7 @@ int arduino::EthernetClass::begin(uint8_t *mac, IPAddress ip, IPAddress dns, IPA
   eth_if->set_network(_ip, _netmask, _gateway);
   eth_if->add_dns_server(_dnsServer1, nullptr);
 
-  auto ret = begin(mac, timeout, responseTimeout);
+  auto ret = _begin(mac, timeout, responseTimeout);
   return ret;
 }
 
diff --git a/libraries/Ethernet/src/Ethernet.h b/libraries/Ethernet/src/Ethernet.h
index 8352a1c4e..2fc2ef240 100644
--- a/libraries/Ethernet/src/Ethernet.h
+++ b/libraries/Ethernet/src/Ethernet.h
@@ -116,6 +116,8 @@ class EthernetClass : public MbedSocketClass {
   constexpr static int maintain () { return DHCP_CHECK_NONE; }
 
 private:
+  int _begin(uint8_t *mac, unsigned long timeout, unsigned long responseTimeout);
+
   volatile EthernetLinkStatus _currentNetworkStatus = Unknown;
   EthernetInterface net;
   EthernetInterface *eth_if = &net;