Kibana dashboards embedded in my website became blank after a while

i could see log traffic data from files like localhost_access_log.2017-09-16.txt but get onto kibana UI, i only see data from 9/24/17, all data earlier than that does not show up.

now i am thinking of downloading accumulated useful log files from ubuntu to local, with the same private key that i used to upload stuff, but in vain. any luck knowing about it?

i created a post just now about that topic as well. humm.:sweat: