FIX - Swapped out modem/gateway. Solved all issues.
Before I say anything, I'd like to say that I've scoured the internet for a solution to my problem with no luck.
Me and a friend have been playing on my server with no problems. When two more friends try to join, they are able to log in. They attempt to start loading chunks but the world does not load for them at all. A minute later they receive a TIMED OUT message. Later on, I asked another friend to try to connect, he was able to join and load the world with no issues at all.
So why is it that two of my friends can play with no issue but the other two can't join at all?
The following is what my current situation is:
Port forwarding is not the issue as I've went as far as opening all ports on my server machine.
I had my firewall completely down at the time.
I asked my friends to lower their firewalls.
There are no white lists or black lists active on the server.
The server machine is capable of it's given task hardware wise.
The server.properties file is not the problem. Port set to 25565, server-ip is blank.
My network adapter driver is up-to-date.
My internet speeds are capable of running a server.
Wired connections to the router+modem aren't faulty.
I've also tried hosting a server (vanilla) on two different machines, but still, two friends can join, two cannot.
I hope I'm not forgetting anything. With all that being said, the only problem I can think of is having a faulty modem, maybe some trouble with my isp? They can connect to other servers. Do I have to update Java on my machine? I haven't done that. All of my friends have updated Java versions.
Sorry for being so extensive but I want to be thorough as I've never seen anything like this.
Thanks for your time.
EDIT: I'd also like to mention that sometimes my friends would get a CONNECTION FORCIBLY CLOSED BY HOST error. This doesn't happen often.
C:\Users\Zachp\Desktop\start>java -Xmx1024M -Xms1024M -jar minecraft_server.1.12.2.jar nogui
[23:35:01] [Server thread/INFO]: Starting minecraft server version 1.12.2
[23:35:01] [Server thread/INFO]: Loading properties
[23:35:01] [Server thread/INFO]: Default game type: SURVIVAL
[23:35:01] [Server thread/INFO]: Generating keypair
[23:35:01] [Server thread/INFO]: Starting Minecraft server on *:25565
[23:35:01] [Server thread/INFO]: Using default channel type
[23:35:01] [Server thread/INFO]: Preparing level "world"
[23:35:02] [Server thread/INFO]: Loaded 488 advancements
[23:35:02] [Server thread/INFO]: Preparing start region for level 0
[23:35:03] [Server thread/INFO]: Preparing spawn area: 22%
[23:35:04] [Server thread/INFO]: Preparing spawn area: 98%
[23:35:04] [Server thread/INFO]: Done (2.414s)! For help, type "help" or "?"
[23:35:24] [User Authenticator #1/INFO]: UUID of player 1tommytux is 37cd08b8-ec40-4a28-bb74-6afbde06f7a5
[23:35:24] [Server thread/INFO]: 1tommytux[/184.57.xxx.69:58538] logged in with entity id 351 at (195.66372837148887, 79.0, 196.02161908321975)
[23:35:24] [Server thread/INFO]: 1tommytux joined the game
[23:36:36] [Server thread/INFO]: 1tommytux has made the advancement [Stone Age]
[23:38:06] [User Authenticator #2/INFO]: UUID of player CaptainMorgan07 is 6b5f5daa-425c-4d2a-ab9a-881688d6f028
[23:38:06] [Server thread/INFO]: CaptainMorgan07[/184.57.xxx.143:54952] logged in with entity id 1689 at (207.44670235956144, 69.0, 256.2662269761075)
[23:38:06] [Server thread/INFO]: CaptainMorgan07 joined the game
[23:38:37] [Server thread/INFO]: CaptainMorgan07 lost connection: Disconnected
[23:38:37] [Server thread/INFO]: CaptainMorgan07 left the game
No. It's not ram. It's probably the location of people verses your wifi. Whatever your wifi carrier or whatever might not allow connections to specific areas in the world. Also your wifi might have a firewall up. But it's 100% not ram
Note: Stop using vanilla and use spigot. You don't have to download any plugins. Spigot is 100% faster and doesn't ever have any errors. Spigot will fix this.
I made a Spigot server. Everything else was the same as before. I lowered my firewalls. Btw my machines are connected via Ethernet. I might try buying a new modem and running Cat 6 ethernet cables to my stuff. I seriously have no clue what the issue could be. My only guess is something fu*ky with my modem. My isp is Spectrum and im using their like off brand Chinese modem haha.
Anyways, here is the pastebin of my Spigot server. CaptainMorgan is the person trying to join, but fails.