// modpack server guide
Flooded City server hosting & setup guide
A Flooded City server needs Java 17 and about 2.5–3.5 GB of RAM for up to 8 players.
Something terrible has happened and the city is in ruins. When trying to gather your thoughts it seems you aren't too safe yet as the water levels are rising.
Summary from Flooded City on Modrinth.
Flooded City is a Forge modpack for Minecraft 1.20.1 with 33 mods. We'd pick our Standard plan (4 GB) for it.
Quick facts
| Loader | Forge |
|---|---|
| Minecraft versions | 1.20.1 |
| Java needed | Java 17 for Minecraft 1.20.1 Java version chart. |
| Mods | 33 modsCounted from the pack's file list on Modrinth. None are marked client-only. |
| RAM | About 2–2.5 GB for 1–3 playersBy player count. |
| Downloads | 167,072 on Modrinth |
| Last updated | March 15, 2024 (version 1.0.0) |
| First published | March 12, 2024 on Modrinth |
| Server support | Required: the pack has mods that must run on the server. |
| Server pack | Not published separatelyHow to build the server. |
| Modrinth tags | adventure, challenging, combat |
Flooded City server files
No. Flooded City has no separate server pack on Modrinth, so the server is built from the .mrpack: the Forge server for Minecraft 1.20.1, plus the pack's overrides folder and the server-side mods its modrinth.index.json lists. A modpack installer does this for you; our guide shows how to make a server for a modpack with no server pack.
How much RAM does a Flooded City server need?
| Players online | RAM | DSN plan |
|---|---|---|
| 1–3 players | About 2–2.5 GB | Standard (4 GB) |
| 4–8 players | About 2.5–3.5 GB | Standard (4 GB) |
| 9–15 players | About 3–4.5 GB | Premium (8 GB)Standard (4 GB) can do if players stay close. |
Estimated from 33 mods on the server with our RAM calculator, not measured: low end if players stay together, high end if they spread out.
Set Java's heap (-Xmx) 10–15% under the RAM you have, about -Xmx3500M on 4 GB. Forge 1.20.1 reads it from user_jvm_args.txt: uncomment the -Xmx line. RAM guide.
Flooded City server requirements
| Java | Java 17 |
|---|---|
| Loader | Forge for Minecraft 1.20.1 |
| CPU | Fast single-core speed (one main thread). |
| RAM | About 2–4.5 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 Flooded City
Standard
4 GB RAM · planned launch price $16/month
At about 33 Forge mods this is a light pack, so 4 GB of RAM covers it for a small group.
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 Standard servers open.
More than 8 players, or lots exploring at once? Go up to Premium (8 GB). 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 a Flooded City server on your own PC
What's specific to Flooded City, 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.
Build them from the .mrpack, as in server files above.
- 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). - 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 Flooded City on DSN
Once we relaunch (join the launch list), on DSN you'd install Flooded City from the panel's Modrinth modpack installer (version 1.0.0), pick Java 17 on the Startup tab and accept the EULA in the console. No port forwarding.
How to play Flooded City with friends
Each player installs Flooded City version 1.0.0 with the Modrinth App or Prism Launcher, the same version as the server, and adds the server's address under Multiplayer.
Different versions of Flooded City 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 Flooded City
Can't keep up! Is the server overloaded? means ticks take longer than 50 ms; more RAM won't fix that once Flooded City has enough (tick lag guide). For Flooded City:
- 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.
Common Flooded City crashes
What a Forge 1.20.1 server running Flooded City hits most. For any other error, paste the log into the free crash log analyzer.
- Wrong Java version. Flooded City 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. - Out of memory. Flooded City (33 mods on the server) needs about 2–2.5 GB for 1–3 players;
java.lang.OutOfMemoryErrormeans it ran out. Out-of-memory fix. - Client-only mod on the server. The Flooded City pack file marks none of its mods client-only, so this usually means one was copied over from a player's mods folder. 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 Flooded City 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 Flooded City past version 1.0.0, back up the world: see updating a modpack server without losing your world.
Bugs in Flooded City itself go to its authors: Discord. Server problems on DSN: hello@dsnservers.com or Discord.
Packs like Flooded City
More: all modpack guides and how to make a modded server.
Run Flooded City on DSN when we relaunch.
Our pick, Standard: 4 GB, planned at $16/month.
DSN Servers isn't affiliated with Flooded City or Modrinth. The pack's name, icon, summary and stats come from Modrinth's public API (checked October 4, 2026).