diff --git a/regression-tests/21-large-rpl/code/router/project-conf.h b/regression-tests/21-large-rpl/code/router/project-conf.h
index bec41cd5e..7f338deca 100644
--- a/regression-tests/21-large-rpl/code/router/project-conf.h
+++ b/regression-tests/21-large-rpl/code/router/project-conf.h
@@ -8,4 +8,4 @@
 #define NBR_TABLE_CONF_MAX_NEIGHBORS             8
 
 #define RPL_CONF_DEFAULT_LIFETIME_UNIT           60
-#define RPL_CONF_DEFAULT_LIFETIME                5
+#define RPL_CONF_DEFAULT_LIFETIME                3