diff --git a/src/api/sockets.c b/src/api/sockets.c
index 2d231739..a6d682cb 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -39,6 +39,8 @@
 
 #include "lwip/opt.h"
 
+extern int zts_errno;
+
 #if LWIP_SOCKET /* don't build if not configured for use in lwipopts.h */
 
 #include "lwip/sockets.h"
@@ -281,6 +283,7 @@ static struct lwip_select_cb *select_cb_list;
 #define sock_set_errno(sk, e) do { \
   const int sockerr = (e); \
   set_errno(sockerr); \
+  zts_errno = sockerr; \
 } while (0)
 
 /* Forward declaration of some functions */
diff --git a/src/core/ipv6/nd6.c b/src/core/ipv6/nd6.c
index 039b7963..475ab3ee 100644
--- a/src/core/ipv6/nd6.c
+++ b/src/core/ipv6/nd6.c
@@ -1644,9 +1644,20 @@ nd6_is_prefix_in_netif(const ip6_addr_t *ip6addr, struct netif *netif)
    * addresses (from autoconfiguration) have no implied subnet assignment, and
    * are thus effectively /128 assignments. See RFC 5942 for more on this. */
   for (i = 0; i < LWIP_IPV6_NUM_ADDRESSES; i++) {
-    if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) &&
+    /*if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) &&
         netif_ip6_addr_isstatic(netif, i) &&
-        ip6_addr_netcmp(ip6addr, netif_ip6_addr(netif, i))) {
+        ip6_addr_netcmp(ip6addr, netif_ip6_addr(netif, i))) {*/
+      int prefix_match = 0;
+    if (ip6_addr_is_zt_6plane(ip6addr)) {
+      prefix_match = ip6_addr_6plane_cmp(ip6addr, netif_ip6_addr(netif, i));
+    }
+    if (ip6_addr_is_zt_rfc4193(ip6addr)) {
+      prefix_match = ip6_addr_rfc4193_cmp(ip6addr, netif_ip6_addr(netif, i));
+    }
+    if (!prefix_match) {
+      prefix_match = ip6_addr_netcmp(ip6addr, netif_ip6_addr(netif, i));
+    }
+    if (ip6_addr_isvalid(netif_ip6_addr_state(netif, i)) && prefix_match) {
       return 1;
     }
   }
diff --git a/src/include/lwip/arch.h b/src/include/lwip/arch.h
index a54ce4f5..58dae33a 100644
--- a/src/include/lwip/arch.h
+++ b/src/include/lwip/arch.h
@@ -199,14 +199,8 @@ typedef uintptr_t mem_ptr_t;
 #include <unistd.h>
 #endif
 #else /* SSIZE_MAX */
-#ifndef _MSC_VER
 typedef int ssize_t;
 #define SSIZE_MAX INT_MAX
-#else
-#include <BaseTsd.h>
-typedef SSIZE_T ssize_t;
-#define SSIZE_MAX INT_MAX
-#endif
 #endif /* SSIZE_MAX */
 
 /* some maximum values needed in lwip code */
diff --git a/src/include/lwip/errno.h b/src/include/lwip/errno.h
index a1dd5b2b..f27b6aff 100644
--- a/src/include/lwip/errno.h
+++ b/src/include/lwip/errno.h
@@ -191,7 +191,7 @@ extern "C" {
 #else /* LWIP_ERRNO_STDINCLUDE */
 /* Define LWIP_ERRNO_INCLUDE to an equivalent of <errno.h> to include the error defines here */
 #ifdef LWIP_ERRNO_INCLUDE
-#include LWIP_ERRNO_INCLUDE
+#include <errno.h>
 #endif /* LWIP_ERRNO_INCLUDE */
 #endif /* LWIP_ERRNO_STDINCLUDE */
 
diff --git a/src/include/lwip/ip6_addr.h b/src/include/lwip/ip6_addr.h
index 29c2a34d..448ffef8 100644
--- a/src/include/lwip/ip6_addr.h
+++ b/src/include/lwip/ip6_addr.h
@@ -160,6 +160,21 @@ typedef struct ip6_addr ip6_addr_t;
 #define ip6_addr_netcmp(addr1, addr2) (ip6_addr_netcmp_zoneless((addr1), (addr2)) && \
                                        ip6_addr_cmp_zone((addr1), (addr2)))
 
+/* Determine if an address *could* be a ZeroTier 6PLANE/Ad-hoc address */
+#define ip6_addr_is_zt_6plane(addr1) (((addr1)->addr[0] & PP_HTONL(0xff000000UL)) == PP_HTONL(0xfc000000UL))
+
+/* Compare first 40 bits of address (ff + first 32 bits of nwid XOR'd with second 32 bits of nwid) */
+#define ip6_addr_6plane_cmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
+                                    ((addr1)->addr[1] & PP_HTONL(0xff000000UL)) == ((addr2)->addr[1] & PP_HTONL(0xff000000UL)))
+
+/* Determine if an address *could* be an RFC4193 address */
+#define ip6_addr_is_zt_rfc4193(addr1) (((addr1)->addr[0] & PP_HTONL(0xff000000UL)) == PP_HTONL(0xfd000000UL))
+
+/* Compare first 72 bits of address (fd + 64 bits of nwid) */
+#define ip6_addr_rfc4193_cmp(addr1, addr2) (((addr1)->addr[0] == (addr2)->addr[0]) && \
+                                    ((addr1)->addr[1] == (addr2)->addr[1]) && \
+                                    ((addr1)->addr[2] & PP_HTONL(0xff000000UL)) == ((addr2)->addr[2] & PP_HTONL(0xff000000UL)))
+
 /* Exact-host comparison *after* ip6_addr_netcmp() succeeded, for efficiency. */
 #define ip6_addr_nethostcmp(addr1, addr2) (((addr1)->addr[2] == (addr2)->addr[2]) && \
                                            ((addr1)->addr[3] == (addr2)->addr[3]))