diff --git a/download_dependencies.sh b/download_dependencies.sh
index 33262c8ddde1..3e156a040657 100755
--- a/download_dependencies.sh
+++ b/download_dependencies.sh
@@ -14,14 +14,14 @@ if [ "x$1" != "xlocked" ]; then
 fi
 
 ## Download LWIP
-LWIP_REPO_URL="https://github.com/ps2dev/lwip.git"
+LWIP_REPO_URL="https://github.com/lwip-tcpip/lwip.git"
 LWIP_REPO_FOLDER="common/external_deps/lwip"
-LWIP_BRANCH_NAME="ps2-v2.0.3"
+LWIP_BRANCH_NAME="STABLE-2_2_1_RELEASE"
 if test ! -d "$LWIP_REPO_FOLDER"; then
   git clone --depth 1 -b $LWIP_BRANCH_NAME $LWIP_REPO_URL "$LWIP_REPO_FOLDER"_inprogress || exit 1
   mv "$LWIP_REPO_FOLDER"_inprogress "$LWIP_REPO_FOLDER"
 else
-  (cd "$LWIP_REPO_FOLDER" && git fetch origin && git reset --hard "origin/${LWIP_BRANCH_NAME}" && git checkout "$LWIP_BRANCH_NAME" && cd - )|| exit 1
+  (cd "$LWIP_REPO_FOLDER" && git fetch origin --tags && git reset --hard "${LWIP_BRANCH_NAME}" && git checkout "$LWIP_BRANCH_NAME" && cd - )|| exit 1
 fi
 
 ## Download libsmb2
diff --git a/ee/network/tcpip/Makefile b/ee/network/tcpip/Makefile
index 4ac9ef2e9728..cae15eb6bf75 100644
--- a/ee/network/tcpip/Makefile
+++ b/ee/network/tcpip/Makefile
@@ -35,9 +35,42 @@ endif
 
 EE_INCS += -I$(LWIP)/src/include -I$(LWIP)/src/include/ipv4
 
-ps2api_OBJECTS = api_lib.o api_msg.o api_netbuf.o err.o sockets.o tcpip.o
-ps2api_IPV4 = icmp.o ip.o ip4.o ip4_addr.o ip4_frag.o inet_chksum.o
-ps2ip_OBJECTS = sys.o lwip_init.o mem.o netif.o pbuf.o stats.o tcp_in.o tcp_out.o udp.o memp.o tcp.o ethernet.o etharp.o raw.o def.o timeouts.o $(ps2api_IPV4) $(ps2api_OBJECTS)
+ps2api_OBJECTS = \
+	api_lib.o \
+	api_msg.o \
+	api_netbuf.o \
+	err.o \
+	sockets.o \
+	tcpip.o
+
+ps2api_IPV4 = \
+	acd.o \
+	icmp.o \
+	ip.o \
+	ip4.o \
+	ip4_addr.o \
+	ip4_frag.o \
+	inet_chksum.o
+
+ps2ip_OBJECTS = \
+	sys.o \
+	lwip_init.o \
+	mem.o \
+	netif.o \
+	pbuf.o \
+	stats.o \
+	tcp_in.o \
+	tcp_out.o \
+	udp.o \
+	memp.o \
+	tcp.o \
+	ethernet.o \
+	etharp.o \
+	raw.o \
+	def.o \
+	timeouts.o \
+	$(ps2api_IPV4) \
+	$(ps2api_OBJECTS)
 
 ifdef PS2IP_DHCP
 ps2ip_OBJECTS += dhcp.o
@@ -82,6 +115,9 @@ $(EE_OBJS_DIR)api_msg.o: $(LWIP)/src/api/api_msg.c
 $(EE_OBJS_DIR)api_netbuf.o: $(LWIP)/src/api/netbuf.c
 	$(EE_CC) $(EE_CFLAGS) $(EE_INCS) -c $< -o $@
 
+$(EE_OBJS_DIR)acd.o: $(LWIP)/src/core/ipv4/acd.c
+	$(EE_CC) $(EE_CFLAGS) $(EE_INCS) -c $< -o $@
+
 $(EE_OBJS_DIR)icmp.o: $(LWIP)/src/core/ipv4/icmp.c
 	$(EE_CC) $(EE_CFLAGS) $(EE_INCS) -c $< -o $@
 
diff --git a/ee/network/tcpip/src/include/arch/cc.h b/ee/network/tcpip/src/include/arch/cc.h
index a8ef6c6abb64..c3be57d3271e 100644
--- a/ee/network/tcpip/src/include/arch/cc.h
+++ b/ee/network/tcpip/src/include/arch/cc.h
@@ -4,6 +4,7 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <stddef.h>
+#include <sys/select.h>
 
 #define PACK_STRUCT_FIELD(x) x __attribute((packed))
 #define PACK_STRUCT_STRUCT __attribute((packed))
diff --git a/ee/network/tcpip/src/include/lwipopts.h b/ee/network/tcpip/src/include/lwipopts.h
index 6b2fd7b79a56..90c45afcfd85 100644
--- a/ee/network/tcpip/src/include/lwipopts.h
+++ b/ee/network/tcpip/src/include/lwipopts.h
@@ -244,6 +244,8 @@
  */
 #define LWIP_CHECKSUM_ON_COPY	1
 
+/* Define LWIP_ERRNO_STDINCLUDE if you want to include <errno.h> here */
+#define LWIP_ERRNO_STDINCLUDE	1
 /*
    ------------------------------------
    ---------- Socket options ----------
diff --git a/ee/network/tcpip/src/ps2ip_internal.h b/ee/network/tcpip/src/ps2ip_internal.h
index 59d333b7399b..bcdd1b9fb9bd 100644
--- a/ee/network/tcpip/src/ps2ip_internal.h
+++ b/ee/network/tcpip/src/ps2ip_internal.h
@@ -11,6 +11,7 @@
 #ifndef IOP_PS2IP_INTERNAL_H
 #define	IOP_PS2IP_INTERNAL_H
 
+#include <sys/select.h>
 #include "lwip/sockets.h"
 
 typedef struct
diff --git a/ee/network/tcpip/src/sys_arch.c b/ee/network/tcpip/src/sys_arch.c
index 3b2371591da5..f67b80700483 100644
--- a/ee/network/tcpip/src/sys_arch.c
+++ b/ee/network/tcpip/src/sys_arch.c
@@ -338,6 +338,12 @@ err_t sys_mbox_trypost(sys_mbox_t *mbox, void *sys_msg)
 	return result;
 }
 
+err_t sys_mbox_trypost_fromisr(sys_mbox_t *mbox, void *msg)
+{
+	// On PS2 EE, ISR and task level are the same, so just call trypost
+	return sys_mbox_trypost(mbox, msg);
+}
+
 void sys_mbox_post(sys_mbox_t *mbox, void *sys_msg)
 {
 	SendMbx(mbox, alloc_msg(), sys_msg);
diff --git a/iop/network/smap/src/imports.lst b/iop/network/smap/src/imports.lst
index ac17ea7e16db..f4247410f152 100644
--- a/iop/network/smap/src/imports.lst
+++ b/iop/network/smap/src/imports.lst
@@ -63,7 +63,7 @@ I_inet_addr
 I_tcpip_input
 I_netif_set_link_up
 I_netif_set_link_down
-I_tcpip_callback_with_block
+I_tcpip_callback
 ps2ip_IMPORTS_end
 #endif
 
diff --git a/iop/system/sysclib/include/ctype.h b/iop/system/sysclib/include/ctype.h
index 08330f297459..d8d2df80176d 100644
--- a/iop/system/sysclib/include/ctype.h
+++ b/iop/system/sysclib/include/ctype.h
@@ -63,6 +63,8 @@ extern "C" {
 /** Blank (space) */
 #define	_B		0x80
 
+extern unsigned char look_ctype_table(char character);
+
 #define	isalpha(c)	(look_ctype_table((unsigned int)(c)) & (_U|_L))
 #define	isupper(c)	(look_ctype_table((unsigned int)(c)) & (_U))
 #define	islower(c)	(look_ctype_table((unsigned int)(c)) & (_L))
diff --git a/iop/tcpip/tcpip-base/include/arch/cc.h b/iop/tcpip/tcpip-base/include/arch/cc.h
index f3b915b0a132..a1b0d7c02e6d 100644
--- a/iop/tcpip/tcpip-base/include/arch/cc.h
+++ b/iop/tcpip/tcpip-base/include/arch/cc.h
@@ -1,8 +1,8 @@
 #ifndef __CC_H__
 #define __CC_H__
 
-#include <errno.h>
 #include <stddef.h>
+#include <sys/time.h>
 
 #define BYTE_ORDER LITTLE_ENDIAN
 
@@ -47,8 +47,6 @@ typedef u32_t			mem_ptr_t;
 #define LWIP_PLATFORM_ASSERT(args)
 #endif
 
-#define atoi(x) strtol(x, NULL, 10)
-
 #define LWIP_NO_STDINT_H	1	//stdint.h does not exist.
 #define LWIP_NO_INTTYPES_H	1	//inttypes.h does not exist.
 
diff --git a/iop/tcpip/tcpip-base/include/lwipopts.h b/iop/tcpip/tcpip-base/include/lwipopts.h
index f3781cc2a7fb..82a12c5e174c 100644
--- a/iop/tcpip/tcpip-base/include/lwipopts.h
+++ b/iop/tcpip/tcpip-base/include/lwipopts.h
@@ -167,6 +167,10 @@
 #define LWIP_DHCP		1
 #endif
 
+/* ---------- ACD options ---------- */
+#define LWIP_ACD		0
+#define LWIP_DHCP_DOES_ACD_CHECK	0
+
 /**
  * DHCP_DOES_ARP_CHECK==1: Do an ARP check on the offered address.
  */
@@ -236,6 +240,8 @@
  */
 #define LWIP_CHECKSUM_ON_COPY	1
 
+/* Use PS2SDK's errno.h instead of lwIP's own errno definitions */
+#define LWIP_ERRNO_STDINCLUDE	1
 /*
    ------------------------------------
    ---------- Socket options ----------
diff --git a/iop/tcpip/tcpip-base/include/stdlib.h b/iop/tcpip/tcpip-base/include/stdlib.h
new file mode 100644
index 000000000000..7f0cb3955702
--- /dev/null
+++ b/iop/tcpip/tcpip-base/include/stdlib.h
@@ -0,0 +1,36 @@
+/*
+# _____     ___ ____     ___ ____
+#  ____|   |    ____|   |        | |____|
+# |     ___|   |____ ___|    ____| |    \    PS2DEV Open Source Project.
+#-----------------------------------------------------------------------
+# Copyright 2001-2004, ps2dev - http://www.ps2dev.org
+# Licenced under Academic Free License version 2.0
+# Review ps2sdk README & LICENSE files for further details.
+*/
+
+/**
+ * @file
+ * Minimal stdlib.h for IOP tcpip
+ * Provides basic functions needed by lwIP on the IOP
+ */
+
+#ifndef __IOP_TCPIP_STDLIB_H__
+#define __IOP_TCPIP_STDLIB_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* atoi - convert string to integer
+ * Implemented as a macro using strtol from sysclib
+ */
+#define atoi(x) strtol(x, NULL, 10)
+
+/* Required for strtol */
+long int strtol(const char *nptr, char **endptr, int base);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __IOP_TCPIP_STDLIB_H__ */
diff --git a/iop/tcpip/tcpip-base/sys_arch.c b/iop/tcpip/tcpip-base/sys_arch.c
index adf8bf3cec5c..9cca38af7824 100644
--- a/iop/tcpip/tcpip-base/sys_arch.c
+++ b/iop/tcpip/tcpip-base/sys_arch.c
@@ -182,6 +182,12 @@ err_t sys_mbox_trypost(sys_mbox_t *mbox, void *msg){
 	return result;
 }
 
+err_t sys_mbox_trypost_fromisr(sys_mbox_t *mbox, void *msg)
+{
+	// On PS2 IOP, ISR and task level are the same, so just call trypost
+	return sys_mbox_trypost(mbox, msg);
+}
+
 void sys_mbox_post(sys_mbox_t *mbox, void *msg)
 {
 	arch_message *MsgPkt;
diff --git a/iop/tcpip/tcpip-netman/src/exports.tab b/iop/tcpip/tcpip-netman/src/exports.tab
index 470bc1fcd03b..f04f753ad27f 100644
--- a/iop/tcpip/tcpip-netman/src/exports.tab
+++ b/iop/tcpip/tcpip-netman/src/exports.tab
@@ -67,6 +67,6 @@ DECLARE_EXPORT_TABLE(ps2ip, 2, 6)
 #endif
 	DECLARE_EXPORT(netif_set_link_up)
 	DECLARE_EXPORT(netif_set_link_down)	//55
-	DECLARE_EXPORT(tcpip_callback_with_block)
+	DECLARE_EXPORT(tcpip_callback)
 	DECLARE_EXPORT(pbuf_coalesce)
 END_EXPORT_TABLE
diff --git a/iop/tcpip/tcpip-netman/src/imports.lst b/iop/tcpip/tcpip-netman/src/imports.lst
index 5237c25a572f..20e7d2b753bf 100644
--- a/iop/tcpip/tcpip-netman/src/imports.lst
+++ b/iop/tcpip/tcpip-netman/src/imports.lst
@@ -50,6 +50,7 @@ I_ReceiveMbx
 thmsgbx_IMPORTS_end
 
 sysclib_IMPORTS_start
+I_look_ctype_table
 I_memset
 I_strcpy
 I_strncpy
@@ -59,8 +60,10 @@ I_strncmp
 I_strtok
 I_strtoul
 I_memcmp
+I_memmove
 I_strtol
 I_strcmp
+I_tolower
 sysclib_IMPORTS_end
 
 sysmem_IMPORTS_start
diff --git a/iop/tcpip/tcpip-netman/src/ps2ip.c b/iop/tcpip/tcpip-netman/src/ps2ip.c
index da3fefb3fade..547aec16713f 100644
--- a/iop/tcpip/tcpip-netman/src/ps2ip.c
+++ b/iop/tcpip/tcpip-netman/src/ps2ip.c
@@ -35,6 +35,9 @@
 
 #include "ps2ip_internal.h"
 
+/* Define errno for IOP module */
+int errno __attribute__((section("data")));
+
 typedef struct pbuf	PBuf;
 typedef struct netif	NetIF;
 typedef struct ip4_addr	IPAddr;
diff --git a/iop/tcpip/tcpip/Makefile b/iop/tcpip/tcpip/Makefile
index fada0932d841..e79977fe4342 100644
--- a/iop/tcpip/tcpip/Makefile
+++ b/iop/tcpip/tcpip/Makefile
@@ -45,9 +45,41 @@ IOP_INCS += \
 	-I$(LWIP)/src/include/ipv4 \
 	-I$(PS2IP_BASE)/include
 
-ps2api_OBJECTS = api_lib.o api_msg.o api_netbuf.o err.o sockets.o tcpip.o
-ps2api_IPV4 = icmp.o ip.o ip4.o ip4_addr.o ip4_frag.o inet_chksum.o
-ps2ip_OBJECTS = sys.o lwip_init.o mem.o netif.o pbuf.o stats.o tcp_in.o tcp_out.o udp.o memp.o tcp.o ethernet.o etharp.o raw.o def.o timeouts.o $(ps2api_IPV4) $(ps2api_OBJECTS)
+ps2api_OBJECTS = \
+	api_lib.o \
+	api_msg.o \
+	api_netbuf.o \
+	err.o \
+	sockets.o \
+	tcpip.o
+
+ps2api_IPV4 = \
+	icmp.o \
+	ip.o \
+	ip4.o \
+	ip4_addr.o \
+	ip4_frag.o \
+	inet_chksum.o
+
+ps2ip_OBJECTS = \
+	sys.o \
+	lwip_init.o \
+	mem.o \
+	netif.o \
+	pbuf.o \
+	stats.o \
+	tcp_in.o \
+	tcp_out.o \
+	udp.o \
+	memp.o \
+	tcp.o \
+	ethernet.o \
+	etharp.o \
+	raw.o \
+	def.o \
+	timeouts.o \
+	$(ps2api_IPV4) \
+	$(ps2api_OBJECTS)
 
 ifdef PS2IP_DHCP
 ps2ip_OBJECTS += dhcp.o
diff --git a/iop/tcpip/tcpip/include/ps2ip.h b/iop/tcpip/tcpip/include/ps2ip.h
index 02897051ddf9..46f0ceb2bc81 100644
--- a/iop/tcpip/tcpip/include/ps2ip.h
+++ b/iop/tcpip/tcpip/include/ps2ip.h
@@ -61,13 +61,7 @@ extern err_t     tcpip_input(struct pbuf *p, struct netif *inp);
 /** Function prototype for functions passed to tcpip_callback() */
 typedef void (*tcpip_callback_fn)(void *ctx);
 
-extern err_t  tcpip_callback_with_block(tcpip_callback_fn function, void *ctx, u8 block);
-
-/**
- * @ingroup lwip_os
- * @see tcpip_callback_with_block
- */
-#define tcpip_callback(f, ctx)  tcpip_callback_with_block(f, ctx, 1)
+extern err_t  tcpip_callback(tcpip_callback_fn function, void *ctx);
 
 /* From include/lwip/netif.h:  */
 extern struct netif *netif_add(struct netif *netif,
@@ -188,7 +182,7 @@ extern const ip_addr_t* dns_getserver(u8 numdns);
 #define I_lwip_fcntl DECLARE_IMPORT(47, lwip_fcntl)
 #define I_etharp_output DECLARE_IMPORT(23, etharp_output)
 #define I_tcpip_input DECLARE_IMPORT(25, tcpip_input)
-#define I_tcpip_callback_with_block DECLARE_IMPORT(56, tcpip_callback_with_block)
+#define I_tcpip_callback DECLARE_IMPORT(56, tcpip_callback)
 #define I_netif_add DECLARE_IMPORT(26, netif_add)
 #define I_netif_find DECLARE_IMPORT(27, netif_find)
 #define I_netif_set_default DECLARE_IMPORT(28, netif_set_default)
diff --git a/iop/tcpip/tcpip/src/exports.tab b/iop/tcpip/tcpip/src/exports.tab
index 470bc1fcd03b..f04f753ad27f 100644
--- a/iop/tcpip/tcpip/src/exports.tab
+++ b/iop/tcpip/tcpip/src/exports.tab
@@ -67,6 +67,6 @@ DECLARE_EXPORT_TABLE(ps2ip, 2, 6)
 #endif
 	DECLARE_EXPORT(netif_set_link_up)
 	DECLARE_EXPORT(netif_set_link_down)	//55
-	DECLARE_EXPORT(tcpip_callback_with_block)
+	DECLARE_EXPORT(tcpip_callback)
 	DECLARE_EXPORT(pbuf_coalesce)
 END_EXPORT_TABLE
diff --git a/iop/tcpip/tcpip/src/imports.lst b/iop/tcpip/tcpip/src/imports.lst
index 8a09318f5a69..a20a3b47af01 100644
--- a/iop/tcpip/tcpip/src/imports.lst
+++ b/iop/tcpip/tcpip/src/imports.lst
@@ -43,6 +43,7 @@ I_ReceiveMbx
 thmsgbx_IMPORTS_end
 
 sysclib_IMPORTS_start
+I_look_ctype_table
 I_memset
 I_strcpy
 I_strncpy
@@ -52,8 +53,10 @@ I_strncmp
 I_strtok
 I_strtoul
 I_memcmp
+I_memmove
 I_strtol
 I_strcmp
+I_tolower
 sysclib_IMPORTS_end
 
 sysmem_IMPORTS_start
diff --git a/iop/tcpip/tcpip/src/ps2ip.c b/iop/tcpip/tcpip/src/ps2ip.c
index 141de1903e5d..1dc8f9ca493d 100644
--- a/iop/tcpip/tcpip/src/ps2ip.c
+++ b/iop/tcpip/tcpip/src/ps2ip.c
@@ -15,6 +15,7 @@
 
 #include <types.h>
 #include <stdio.h>
+#include <errno.h>
 #include <intrman.h>
 #include <loadcore.h>
 #include <thbase.h>
@@ -34,6 +35,9 @@
 
 #include "ps2ip_internal.h"
 
+/* Define errno for IOP module */
+int errno __attribute__((section("data")));
+
 typedef struct pbuf	PBuf;
 typedef struct netif	NetIF;
 typedef struct ip4_addr	IPAddr;