diff --git a/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c b/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c
index b565e6683a86a1c9b7ec6cbdbf0ca50cff5e9f49..adf1eb8b403b0e5ff52d55a2e549e7a99383eb4e 100644
--- a/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c
+++ b/sys/net/gnrc/network_layer/ndp/gnrc_ndp.c
@@ -678,19 +678,17 @@ void gnrc_ndp_retrans_nbr_sol(gnrc_ipv6_nc_t *nc_entry)
             }
         }
         else if (nc_entry->probes_remaining <= 1) {
-#ifdef MODULE_GNRC_SIXLOWPAN_ND_ROUTER
-            if (nc_entry->iface != KERNEL_PID_UNDEF) {
-                gnrc_ipv6_netif_t *ipv6_iface = gnrc_ipv6_netif_get(nc_entry->iface);
-                if ((ipv6_iface->flags & GNRC_IPV6_NETIF_FLAGS_SIXLOWPAN) &&
-                    (ipv6_iface->flags & GNRC_IPV6_NETIF_FLAGS_ROUTER) &&
-                    (gnrc_ipv6_nc_get_type(nc_entry) != GNRC_IPV6_NC_TYPE_GC)) {
-                    /* don't remove non-gc entrys on 6LRs:
-                     * https://tools.ietf.org/html/rfc6775#section-6 */
-                    gnrc_ndp_internal_set_state(nc_entry, GNRC_IPV6_NC_STATE_UNREACHABLE);
-                    return;
-                }
-            }
-#endif
+
+            /* For a 6LoWPAN router entries may be set to UNREACHABLE instead
+             * of removing them, since RFC6775, section 6
+             * (https://tools.ietf.org/html/rfc6775#section-6) says: "if NUD on
+             * the router determines that the host is UNREACHABLE (based on the
+             * logic in [RFC4861]), the NCE SHOULD NOT be deleted but rather
+             * retained until the Registration Lifetime expires." However, this
+             * "SHOULD NOT" is not implemented to circumvent NCEs going into
+             * UNREACHABLE forever and in order to save some memory in the
+             * neighbor cache. */
+
             DEBUG("ndp: Remove nc entry %s for interface %" PRIkernel_pid "\n",
                   ipv6_addr_to_str(addr_str, &nc_entry->ipv6_addr, sizeof(addr_str)),
                   nc_entry->iface);