diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index a6c8b0a8a6..03897e77bf 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -1863,6 +1863,12 @@ isc__nm_socket_tcp_nodelay(uv_os_sock_t fd);
  * Disables Nagle's algorithm on a TCP socket (sets TCP_NODELAY).
  */
 
+isc_result_t
+isc__nm_socket_min_mtu(uv_os_sock_t fd, sa_family_t sa_family);
+/*%<
+ * Use minimum MTU on IPv6 sockets
+ */
+
 void
 isc__nm_set_network_buffers(isc_nm_t *nm, uv_handle_t *handle);
 /*%>
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index eafce4ec1c..8f5589cd6e 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -3263,6 +3263,27 @@ isc__nm_socket_tcp_nodelay(uv_os_sock_t fd) {
 #endif
 }
 
+isc_result_t
+isc__nm_socket_min_mtu(uv_os_sock_t fd, sa_family_t sa_family) {
+	if (sa_family != AF_INET6) {
+		return (ISC_R_SUCCESS);
+	}
+#ifdef IPV6_USE_MIN_MTU
+	if (setsockopt_on(fd, IPPROTO_IPV6, IPV6_USE_MIN_MTU) == -1) {
+		return (ISC_R_FAILURE);
+	}
+#elif defined(IPV6_MTU)
+	if (setsockopt(fd, IPPROTO_IPV6, IPV6_MTU, &(int){ 1280 },
+		       sizeof(int)) == -1) {
+		return (ISC_R_FAILURE);
+	}
+#else
+	UNUSED(fd);
+#endif
+
+	return (ISC_R_SUCCESS);
+}
+
 void
 isc__nm_set_network_buffers(isc_nm_t *nm, uv_handle_t *handle) {
 	int32_t recv_buffer_size = 0;
diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index b033e71cc8..4e187d31e2 100644
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -342,6 +342,8 @@ isc_nm_tcpconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
 		return;
 	}
 
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
+
 	ievent = isc__nm_get_netievent_tcpconnect(mgr, sock, req);
 
 	if (isc__nm_in_netthread()) {
@@ -525,7 +527,7 @@ isc__nm_async_tcplisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(sock->parent != NULL);
 	REQUIRE(sock->tid == isc_nm_tid());
 
-	/* TODO: set min mss */
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
 
 	r = uv_tcp_init(&worker->loop, &sock->uv_handle.tcp);
 	UV_RUNTIME_CHECK(uv_tcp_init, r);
diff --git a/lib/isc/netmgr/tcpdns.c b/lib/isc/netmgr/tcpdns.c
index fcce42df97..1b84b50da7 100644
--- a/lib/isc/netmgr/tcpdns.c
+++ b/lib/isc/netmgr/tcpdns.c
@@ -297,6 +297,8 @@ isc_nm_tcpdnsconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
 		return;
 	}
 
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
+
 	/* 2 minute timeout */
 	result = isc__nm_socket_connectiontimeout(sock->fd, 120 * 1000);
 	RUNTIME_CHECK(result == ISC_R_SUCCESS);
@@ -489,7 +491,7 @@ isc__nm_async_tcpdnslisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(sock->parent != NULL);
 	REQUIRE(sock->tid == isc_nm_tid());
 
-	/* TODO: set min mss */
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
 
 	r = uv_tcp_init(&worker->loop, &sock->uv_handle.tcp);
 	UV_RUNTIME_CHECK(uv_tcp_init, r);
diff --git a/lib/isc/netmgr/tlsdns.c b/lib/isc/netmgr/tlsdns.c
index af5362f7e6..369eac1497 100644
--- a/lib/isc/netmgr/tlsdns.c
+++ b/lib/isc/netmgr/tlsdns.c
@@ -351,6 +351,8 @@ isc_nm_tlsdnsconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
 		goto failure;
 	}
 
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
+
 	/* 2 minute timeout */
 	result = isc__nm_socket_connectiontimeout(sock->fd, 120 * 1000);
 	RUNTIME_CHECK(result == ISC_R_SUCCESS);
@@ -560,7 +562,7 @@ isc__nm_async_tlsdnslisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(sock->parent != NULL);
 	REQUIRE(sock->tid == isc_nm_tid());
 
-	/* TODO: set min mss */
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
 
 	r = uv_tcp_init(&worker->loop, &sock->uv_handle.tcp);
 	UV_RUNTIME_CHECK(uv_tcp_init, r);
diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index e8ef4100f1..624932bc98 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -439,6 +439,8 @@ isc__nm_async_udplisten(isc__networker_t *worker, isc__netievent_t *ev0) {
 	REQUIRE(sock->parent != NULL);
 	REQUIRE(sock->tid == isc_nm_tid());
 
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
+
 #if HAVE_DECL_UV_UDP_RECVMMSG
 	uv_init_flags |= UV_UDP_RECVMMSG;
 #endif
@@ -1031,6 +1033,8 @@ isc_nm_udpconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
 
 	(void)isc__nm_socket_disable_pmtud(sock->fd, sa_family);
 
+	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
+
 	event = isc__nm_get_netievent_udpconnect(mgr, sock, req);
 
 	if (isc__nm_in_netthread()) {