When i join i get the minecraft dirt-screen saying the server is stopped and when i go to my server on aternos.org/server i see it shutting down.
The console says:
[09:43:00] [Server thread/WARN]: Can't keep up! Is the server overloaded? Running 3067ms or 61 ticks behind
[09:43:00] [WorldGen-Worker-1/ERROR]: Requested chunk : 25859 1874990
[09:43:00] [WorldGen-Worker-1/ERROR]: Region bounds : 25859 1874991 | 25859 1874991
[09:43:00] [Server thread/ERROR]: Encountered an unexpected exception
h: Exception generating new chunk
at net.minecraft.server.MinecraftServer.w(SourceFile:727) ~inecraft_server.jar:?]
at sn.w(SourceFile:357) ~inecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.v(SourceFile:656) ~inecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:559) inecraft_server.jar:?]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_144]
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: We are asking a region for a chunk out of bound | 25859 1874990
at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357) ~[?:1.8.0_144]
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1895) ~[?:1.8.0_144]
at tb.c(SourceFile:126) ~inecraft_server.jar:?]
at tj.a(SourceFile:85) ~inecraft_server.jar:?]
at tk.c(SourceFile:123) ~inecraft_server.jar:?]
at tc.i_(SourceFile:220) ~inecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.w(SourceFile:723) ~inecraft_server.jar:?]
... 4 more
Caused by: java.lang.RuntimeException: We are asking a region for a chunk out of bound | 25859 1874990
at th.c(SourceFile:118) ~inecraft_server.jar:?]
at axt.y(SourceFile:45) ~inecraft_server.jar:?]
at th.a_(SourceFile:124) ~inecraft_server.jar:?]
at axw.c(SourceFile:350) ~inecraft_server.jar:?]
at aey.a(SourceFile:714) ~inecraft_server.jar:?]
at ayc.a(SourceFile:285) ~inecraft_server.jar:?]
at bom.b(SourceFile:116) ~inecraft_server.jar:?]
at tv.a(SourceFile:15) ~inecraft_server.jar:?]
at tp.a(SourceFile:35) ~inecraft_server.jar:?]
at bmu.a(SourceFile:95) ~inecraft_server.jar:?]
at tw.a(SourceFile:62) ~inecraft_server.jar:?]
at tw.a(SourceFile:25) ~inecraft_server.jar:?]
at acr$a.a(SourceFile:130) ~inecraft_server.jar:?]
at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:602) ~[?:1.8.0_144]
at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:577) ~[?:1.8.0_144]
at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:443) ~[?:1.8.0_144]
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) ~[?:1.8.0_144]
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) ~[?:1.8.0_144]
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692) ~[?:1.8.0_144]
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157) ~[?:1.8.0_144]
[09:43:00] [Server thread/ERROR]: This crash report has been saved to: /aternos/server/./crash-reports/crash-2018-08-02_09.43.00-server.txt
[09:43:00] [Server thread/INFO]: Stopping server
[09:43:00] [Server thread/INFO]: Saving players
[09:43:01] [Server thread/INFO]: Saving worlds
[09:43:01] [Server thread/INFO]: Saving chunks for level 'world'/overworld
[09:43:01] [Server thread/INFO]: Saving chunks for level 'world'/the_nether
[09:43:01] [Server thread/INFO]: Saving chunks for level 'world'/the_end
[09:43:02] [Server Shutdown Thread/INFO]: Stopping server
[09:43:02] [Server Shutdown Thread/INFO]: Saving players
I have tried everything i know but it still won't work 
This started when i accientally teleported outside the world border.
The first times i joined i had a couple of seconds on the server before it crashed so i managed to do a /kill but after that the server just stopped immedeately.