So I've read up on other people's post on this subject but none of them seem to help.
This is what my log says
[01:23:35] [Server thread/INFO]: Starting minecraft server version 1.12.2
[01:23:35] [Server thread/INFO]: Loading properties
[01:23:35] [Server thread/INFO]: Default game type: SURVIVAL
[01:23:35] [Server thread/INFO]: Generating keypair
[01:23:36] [Server thread/INFO]: Starting Minecraft server on *:48874
[01:23:36] [Server thread/INFO]: Using epoll channel type
[01:23:36] [Server thread/INFO]: Preparing level "world"
[01:23:37] [Server thread/INFO]: Loaded 488 advancements
[01:23:37] [Server thread/INFO]: Preparing start region for level 0
[01:23:38] [Server thread/INFO]: Preparing spawn area: 0%
[01:23:39] [Server thread/INFO]: Preparing spawn area: 46%
[01:23:40] [Server thread/INFO]: Done (3.972s)! For help, type "help" or "?"
[01:23:40] [Server thread/INFO]: Starting GS4 status listener
[01:23:40] [Query Listener #1/INFO]: Query running on 0.0.0.0:48874
[01:23:52] [User Authenticator #1/INFO]: UUID of player DongHyun2001 is 1608b856-c472-42c7-91c7-51032b9359de
[01:23:52] [Server thread/INFO]: DongHyun2001[/76.211.205.80:58536] logged in with entity id 491 at (133.64662720084314, 67.0, 266.30000001192093)
[01:23:52] [Server thread/INFO]: DongHyun2001 joined the game
[01:24:33] [Server thread/INFO]: DongHyun2001 lost connection: Disconnected
[01:24:33] [Server thread/INFO]: DongHyun2001 left the game
[01:24:40] [User Authenticator #2/INFO]: UUID of player DongHyun2001 is 1608b856-c472-42c7-91c7-51032b9359de
[01:24:40] [Server thread/INFO]: DongHyun2001[/76.211.205.80:58544] logged in with entity id 1373 at (134.69999998807907, 67.0, 266.3016536234645)
[01:24:40] [Server thread/INFO]: DongHyun2001 joined the game
[01:25:19] [Server thread/INFO]: DongHyun2001 lost connection: Disconnected
[01:25:19] [Server thread/INFO]: DongHyun2001 left the game
[01:27:47] [User Authenticator #3/INFO]: UUID of player DongHyun2001 is 1608b856-c472-42c7-91c7-51032b9359de
[01:27:47] [Server thread/INFO]: DongHyun2001[/76.211.205.80:58637] logged in with entity id 2100 at (134.69999998807907, 67.0, 266.3016536234645)
[01:27:47] [Server thread/INFO]: DongHyun2001 joined the game
[01:28:36] [Server thread/INFO]: DongHyun2001 lost connection: Disconnected
[01:28:36] [Server thread/INFO]: DongHyun2001 left the game
[01:28:40] [Server thread/INFO]: Saving...
[01:28:40] [Server thread/INFO]: Saved the world
Can someone please help? Thank you.