nc: cancel timer set by `gnrc_ndp_rtr_sol_handle` in `gnrc_ipv6_nc_remove`.

sys/net/gnrc/network_layer/ipv6/nc/gnrc_ipv6_nc.c

@@ -163,6 +163,13 @@ void gnrc_ipv6_nc_remove(kernel_pid_t iface, const ipv6_addr_t *ipv6_addr)
 #endif
 #ifdef MODULE_GNRC_SIXLOWPAN_ND_ROUTER
         xtimer_remove(&entry->type_timeout);
+
+        gnrc_ipv6_netif_t *if_entry = gnrc_ipv6_netif_get(iface);
+
+        if ((if_entry != NULL) && (if_entry->rtr_adv_msg.content.ptr == (char *) entry)) {
+            /* cancel timer set by gnrc_ndp_rtr_sol_handle */
+            xtimer_remove(&if_entry->rtr_adv_timer);
+        }
 #endif
 #if defined(MODULE_GNRC_NDP_ROUTER) || defined(MODULE_GNRC_SIXLOWPAN_ND_BORDER_ROUTER)
         xtimer_remove(&entry->rtr_adv_timer);