// modpack server guide
ATM9 To the Sky server hosting & setup guide
An ATM9 To the Sky server needs Java 17 and about 9–11 GB of RAM for up to 8 players.
A sky-world spin-off of All the Mods 9 on Forge 1.20.1: you start on a tree in the void and automate your way to tech and magic endgame resources.
Pack details checked by hand against All the Mods 9: To the Sky on CurseForge on October 4, 2026.
All the Mods 9: To the Sky is a Forge modpack for Minecraft 1.20.1 with 309 mods. We'd pick our Heavy plan (12 GB) for it.
- The pack's own default server.properties (in its GitHub repository) sets level-type=skyblockbuilder:skyblock and allow-flight=true. Keep those settings if you set the server up by hand, so the world generates as a sky world.
- See also: All the Mods 10: To the Sky server guide and All the Mods 9 server guide.
Quick facts
| Loader | Forge |
|---|---|
| Minecraft versions | 1.20.1 |
| Java needed | Java 17 for Minecraft 1.20.1 Java version chart. |
| Mods | 309 modsThe number of mods CurseForge lists for the pack, client-side ones included. |
| RAM | About 8–9 GB for 1–3 playersBy player count. |
| Downloads | 3,096,439 on CurseForgeAs of October 4, 2026. |
| Latest version | April 24, 2026 (version 1.1.9)The newest version when we checked on October 4, 2026. |
| Official server files | Download pagePublished next to each version on CurseForge, for example ServerFiles-1.1.9 for version 1.1.9. |
| Where to get it | All the Mods 9: To the Sky on CurseForge |
| Tags | skyblock, magic, quests, tech |
ATM9 To the Sky server files
ATM9 To the Sky's authors publish official server files. Published next to each version on CurseForge, for example ServerFiles-1.1.9 for version 1.1.9. Get the official server files.
Use the server files for the exact version your players install: a server and client on different pack versions won't connect.
How much RAM does an ATM9 To the Sky server need?
| Players online | RAM | DSN plan |
|---|---|---|
| 1–3 players | About 8–9 GB | Heavy (12 GB)Premium (8 GB) can do if players stay close. |
| 4–8 players | About 9–11 GB | Heavy (12 GB) |
| 9–15 players | About 10.5–13.5 GB | Heavy (12 GB) if players stay closeMore than 12 GB if they spread out. |
Estimated from 309 mods with our RAM calculator, not measured: low end if players stay together, high end if they spread out.
With 9–15 players spread across the map, ATM9 To the Sky can need more than 12 GB, our biggest plan. A lower view distance and a pre-generated world help it fit; past that, a host with bigger plans is the better choice.
Set Java's heap (-Xmx) 10–15% under the RAM you have, about -Xmx10500M on 12 GB. Forge 1.20.1 reads it from user_jvm_args.txt: uncomment the -Xmx line. RAM guide.
ATM9 To the Sky server requirements
| Java | Java 17 |
|---|---|
| Loader | Forge for Minecraft 1.20.1 |
| CPU | Fast single-core speed (one main thread). With 309 mods, the first start takes minutes. |
| RAM | About 8–13.5 GB for 1–15 players (table above) |
| Disk | The server files, a growing world and backups |
| Network | TCP port 25565 open to players |
Recommended plan
Our pick for ATM9 To the Sky
Heavy
12 GB RAM · planned launch price $42/month
The authors don't publish RAM advice, and with 309 mods on CurseForge's list this is a heavy pack even though a sky world starts small, so 12 GB keeps it clear of out-of-memory crashes.
Ordering is closed until we relaunch. We aren't taking orders or payments while we move to new hardware. Join the launch list and we'll email you when Heavy servers open.
Heavy is our biggest plan. Not sure? Email hello@dsnservers.com.
Planned launch price in USD, billed monthly once ordering opens, with a 7-day refund window.
How to make an ATM9 To the Sky server on your own PC
What's specific to ATM9 To the Sky, step by step. The full walkthrough for any pack: how to make a modded Minecraft server.
- Install Java 17.
Check with
java -version. Java version chart. - Get the server files.
Download the official server files for the version your players use and unzip them into an empty folder. Follow the readme that comes with them.
- Start it and accept the EULA.
Run the start script in the server files, or the
run.sh/run.batthe Forge 1.20.1 installer writes, then seteula=trueineula.txtif you accept Mojang's EULA (EULA step). With 309 mods, the first start takes minutes. - Set the RAM with
-Xmx, sized from the table above. - Let friends connect: forward TCP 25565, or use a tunnel or host behind CGNAT (can't connect?).
Or run ATM9 To the Sky on DSN
Once we relaunch (join the launch list), on DSN you'd install ATM9 To the Sky from the panel's CurseForge modpack installer, pick Java 17 on the Startup tab and accept the EULA in the console. No port forwarding.
How to play ATM9 To the Sky with friends
Each player installs ATM9 To the Sky with the CurseForge app or Prism Launcher, the same version as the server, and adds the server's address under Multiplayer.
Different versions of ATM9 To the Sky on the server and a client show up as Mismatched mod channel list or mod rejections. Why friends can't join, timeouts included.
Lag and performance on ATM9 To the Sky
Can't keep up! Is the server overloaded? means ticks take longer than 50 ms; more RAM won't fix that once ATM9 To the Sky has enough (tick lag guide). For ATM9 To the Sky:
- Measure first: spark's
/spark tpsand profiler work on 1.20.1 and name the mod or machine using the tick time. - Distances:
view-distance=8and a lowersimulation-distanceinserver.properties. - Pre-generate: Chunky for 1.20.1,
/chunky radius 3000then/chunky start, before people explore. - Chunk loaders keep machines running with nobody nearby; in a pack this size, dozens add up.
Common ATM9 To the Sky crashes
What a Forge 1.20.1 server running ATM9 To the Sky hits most. For any other error, paste the log into the free crash log analyzer.
- Out of memory. ATM9 To the Sky (309 mods) needs about 8–9 GB for 1–3 players;
java.lang.OutOfMemoryErrormeans it ran out. Out-of-memory fix. - Wrong Java version. ATM9 To the Sky on Minecraft 1.20.1 needs Java 17. Started on Java 8, it stops with
UnsupportedClassVersionError: ... class file version 61.0, this version of the Java Runtime only recognizes class file versions up to 52.0. Java version fix. - Client-only mod on the server. This one shows up when the mods folder is copied from a player's game instead of installed as a server. Check a mods list with the client-or-server-side checker. Client-only mod fix.
- After adding or updating a mod. Mods you add to ATM9 To the Sky by hand usually crash it with a missing dependency or a mixin conflict.
- Ticking entity or block entity. The crash report names it and gives its coordinates. Ticking entity fix.
Updates and support
Before moving ATM9 To the Sky past version 1.1.9, back up the world: see updating a modpack server without losing your world.
Bugs in ATM9 To the Sky itself go to its authors: issue tracker. Server problems on DSN: hello@dsnservers.com or Discord.
Packs like ATM9 To the Sky
More: all modpack guides and how to make a modded server.
Run ATM9 To the Sky on DSN when we relaunch.
Our pick, Heavy: 12 GB, planned at $42/month.
DSN Servers isn't affiliated with All the Mods 9: To the Sky or CurseForge. We wrote the summary and checked the pack's facts by hand on October 4, 2026. Sources: curseforge.com, curseforge.com (2), api.cfwidget.com, github.com.