by executing
mongos --configdb ip1:port1, ip2:port2, ip3:port3 --port 25001
I get the error:
Thu Nov 8 21:00:38 [Balancer] SyncClusterConnection connecting to [ip1:port1]
Thu Nov 8 21:00:38 [Balancer] SyncClusterConnection connecting to [ip2:port2]
Thu Nov 8 21:00:38 [Balancer] SyncClusterConnection connecting to [ip3:port3]
Thu Nov 8 21:00:38 [Balancer] scoped connection to ip1:port1, ip2:port2, ip3:port3 not being returned to the pool
Thu Nov 8 21:00:38 [Balancer] caught exception while doing balance: error checking clock skew of cluster ip1:port1, ip2:port2, ip3:port3 :: caused by :: 13650 clock skew of the cluster ip2:port2, ip3:port3 is too far out of bounds to allow distributed locking.