Internal Server Error

[FuLagann]

So I was playing on a server that is hosted by my friend, but when I left and came back it doesn't let me back on only saying "Internal Server Error". We did not change any of the mods whilst I was away or anything. He is also hosting it on the same Wi-Fi network that I am using, so I have been using his internal IP instead of his external IP. The external IP does not work with the fact that we are using the same network, and his internal IP is still the same that it was before.

 

We are running:

- MC 1.7.10

- Forge 1.7.10  10.13.4.1448

- 36 Mods

 

Other people can get on and play just fine, but I am unable to for some reason, and another person had the same problem, but couldn't get on in the beginning.

 

P.S. I made sure everyone is running the same thing with the same mods, and logs will be posted soon

[FuLagann]

Logs:

 

[13:59:17] [user Authenticator #2/INFO]: UUID of player Fulagann is 00d64f75-44a1-4600-8c5e-967da33ca8a1
[13:59:18] [server thread/INFO]: Fulagann[/10.0.0.2:52584] logged in with entity id 1281 at (440.4902246942252, 65.23152379758702, -2208.876882721954)
[13:59:18] [server thread/INFO]: Fulagann (formerly known as Fuonline) joined the game
[13:59:18] [server thread/WARN]: Failed to handle packet for /##.#.#.#:52584
java.lang.NullPointerException
at cpw.mods.fml.common.network.internal.FMLProxyPacket.func_148833_a(FMLProxyPacket.java:101) ~[FMLProxyPacket.class:?]
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:212) ~[ej.class:?]
at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:165) [nc.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:659) [MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:334) [lt.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427) [MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]
[13:59:19] [server thread/INFO]: Fulagann lost connection: TextComponent{text='Internal server error', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null}}
[13:59:19] [server thread/INFO]: Fulagann left the game