// modpack server guide

Simple Realism server hosting & setup guide

A Simple Realism server needs Java 21 and about 2–3 GB of RAM for up to 8 players.

This Modpack Aims to Make Minecraft More Realistic!

Summary from Simple Realism on Modrinth.

By DSN Servers · Updated October 2026 · Fabric · Minecraft 1.21.1 · Java Edition

Simple Realism is a Fabric modpack for Minecraft 1.21.1 with 65 mods, 40 of which run on the server. We'd pick our Standard plan (4 GB) for it.

Quick facts

Loader	Fabric
Minecraft versions	1.21.1
Java needed	Java 21 for Minecraft 1.21.1 Java version chart.
Mods	40 run on the server65 in the pack. The other 25 are client-only, and the server skips them.
RAM	About 2–2.5 GB for 1–3 playersBy player count.
Downloads	141,844 on Modrinth
Last updated	October 8, 2025 (version v2)
First published	September 10, 2023 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

Simple Realism server files

No. Simple Realism has no separate server pack on Modrinth, so the server is built from the .mrpack: the Fabric server for Minecraft 1.21.1, 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 Simple Realism server need?

Players online	RAM	DSN plan
1–3 players	About 2–2.5 GB	Standard (4 GB)
4–8 players	About 2–3 GB	Standard (4 GB)
9–15 players	About 2.5–4.5 GB	Premium (8 GB)Standard (4 GB) can do if players stay close.

Estimated from 40 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. Fabric 1.21.1 takes it in the java command (-Xmx), usually in the start script. RAM guide.

Simple Realism server requirements

Java	Java 21
Loader	Fabric for Minecraft 1.21.1
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 Simple Realism

Standard

4 GB RAM · planned launch price $16/month

At about 40 Fabric 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.

Join the launch list Compare all plans

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 Simple Realism server on your own PC

What's specific to Simple Realism, step by step. The full walkthrough for any pack: how to make a modded Minecraft server.

Install Java 21.
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 java -jar on the Fabric 1.21.1 server launcher, then set eula=true in eula.txt if 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 Simple Realism on DSN

Once we relaunch (join the launch list), on DSN you'd install Simple Realism from the panel's Modrinth modpack installer (version v2), pick Java 21 on the Startup tab and accept the EULA in the console. No port forwarding.

How to play Simple Realism with friends

Each player installs Simple Realism version v2 with the Modrinth App or Prism Launcher, the same version as the server, and adds the server's address under Multiplayer.

Different versions of Simple Realism 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 Simple Realism

Can't keep up! Is the server overloaded? means ticks take longer than 50 ms; more RAM won't fix that once Simple Realism has enough (tick lag guide). For Simple Realism:

Measure first: spark's /spark tps and profiler work on 1.21.1 and name the mod or machine using the tick time.
Distances: view-distance=8 and a lower simulation-distance in server.properties.
Pre-generate: Chunky for 1.21.1, /chunky radius 3000 then /chunky start, before people explore.

Common Simple Realism crashes

What a Fabric 1.21.1 server running Simple Realism hits most. For any other error, paste the log into the free crash log analyzer.

Wrong Java version. Simple Realism on Minecraft 1.21.1 needs Java 21. Started on Java 17, it stops with UnsupportedClassVersionError: ... class file version 65.0, this version of the Java Runtime only recognizes class file versions up to 61.0. Java version fix.
Out of memory. Simple Realism (40 mods on the server) needs about 2–2.5 GB for 1–3 players; java.lang.OutOfMemoryError means it ran out. Out-of-memory fix.
Client-only mod on the server. Simple Realism includes 25 client-only mods, which a server install skips; copying a player's mods folder brings them back and stops the 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 Simple Realism 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 Simple Realism past version v2, back up the world: see updating a modpack server without losing your world.

Bugs in Simple Realism itself go to its authors: Discord. Server problems on DSN: hello@dsnservers.com or Discord.

More: all modpack guides and how to make a modded server.

Run Simple Realism on DSN when we relaunch.

Our pick, Standard: 4 GB, planned at $16/month.

Join the launch list

DSN Servers isn't affiliated with Simple Realism or Modrinth. The pack's name, icon, summary and stats come from Modrinth's public API (checked October 4, 2026).