disconnected from server

so ive leave this for a month and now its became like this.. can connect,can generate world, but then its like not responding after a while its responding for 1 second and then kicks me out.. I'm the only one on my server...

[04:23:04] [Server thread/INFO]: Starting minecraft server version 1.12.2
[04:23:04] [Server thread/INFO]: Loading properties
[04:23:04] [Server thread/INFO]: Default game type: SURVIVAL
[04:23:04] [Server thread/INFO]: Generating keypair
[04:23:04] [Server thread/INFO]: Starting Minecraft server on *:47136
[04:23:04] [Server thread/INFO]: Using epoll channel type
[04:23:05] [Server thread/WARN]: **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!
[04:23:05] [Server thread/WARN]: The server will make no attempt to authenticate usernames. Beware.
[04:23:05] [Server thread/WARN]: While this makes the game possible to play without internet access, it also opens up the ability for hackers to connect with any username they choose.
[04:23:05] [Server thread/WARN]: To change this, set "online-mode" to "true" in the server.properties file.
[04:23:05] [Server thread/INFO]: Preparing level "world"
[04:23:07] [Server thread/INFO]: Loaded 488 advancements
[04:23:07] [Server thread/INFO]: Preparing start region for level 0
[04:23:08] [Server thread/INFO]: Preparing spawn area: 0%
[04:23:09] [Server thread/INFO]: Preparing spawn area: 21%
[04:23:10] [Server thread/INFO]: Preparing spawn area: 52%
[04:23:11] [Server thread/INFO]: Done (5.909s)! For help, type "help" or "?"
[04:23:11] [Server thread/INFO]: Starting GS4 status listener
[04:23:11] [Query Listener #1/INFO]: Query running on 0.0.0.0:47136
[04:23:21] [Server thread/INFO]: Trytomiss2[/180.241.185.248:22811] logged in with entity id 272 at (171.13749998807907, 65.0, 78.17345082610616)
[04:23:21] [Server thread/INFO]: Trytomiss2 joined the game
[04:23:24] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2647ms behind, skipping 52 tick(s)
[04:24:22] [Server thread/INFO]: Trytomiss2 lost connection: Disconnected
[04:24:22] [Server thread/INFO]: Trytomiss2 left the game

another way.. I leave this server and I want my frined to make one but then my friend connects fine but I'm stuck at building terrain then I got disconnected.. wow

FYI my internet runs on 9MB/s

Connection Lost

Internal Exception: Java.io.IOException: An existing connection was forcibly closed by the remote host

Back to server lost

from Indonesia.. usually its normal until this day

isp I'm not sure.. indihome I guess its this

Failed to connect to the server

Failed to Login: Invalid session (Try restarting the game and the Launcher)

Back to server list

I have restart it but still like this

also no I never mod

of course I'm on cracked.. also its still happen same

idk software but no other server works fine

no and idk

I'm playing minecraft clean I don't like modding

already did that since first game..

just after got in they load but like no respond ping high but after it respond I got kicked

yes I can open the server

how? I don't get it I follow what the site says