Valheim dedicated server, what the official docs don't tell you

The official Valheim dedicated server guide gets you running. It does not warn you about the things that bite long-running servers six months in. This post is the missing footnotes.

World file size grows. A lot.

A Valheim world starts around 10 to 30 MB. After a year of an active 4-player server it can be 800 MB to 1.5 GB. Reasons:

• Every explored region is permanently saved at full detail.
• Item drops on the ground persist (you've seen the "items vanished" complaints, but most of the time they vanish from view, not from save).
• Built structures, dropped tombstones, abandoned bases, all stay in the world file.

Implication: back up the .db AND the .fwl every time, and keep retention longer than you think. A corrupted save with one good backup from "a few days ago" can still mean weeks of lost progress.

The 10-player wall

Valheim's networking does not gracefully scale past about 10 simultaneous players. Past that, you will see:

• Boats rubber-banding for distant players.
• Mobs spawning incorrectly or duplicating.
• Increased "you have been disconnected" events on tile loads.

This is not a hosting issue. It is engine-level. If your group wants to grow beyond 10, plan to split worlds or accept that the experience will degrade.

"Ship vanished" is almost always physics, not bugs

The single most common "we lost progress" report on Valheim servers: docked ship is gone when players log in.

Causes, in order of likelihood:

1. Server restarted while ship was loaded near unloaded terrain. The ship dropped, glitched into terrain, and is "below the world" or stuck inside a rock.
2. Another player wandered near the dock and a serpent attacked it offscreen.
3. Wind / current physics drifted it during a chunk reload.

Prevention:

• Dock ships in fully built, walled harbors with a workbench nearby (prevents enemy spawns in the area).
• Store boats on land using a portable workbench's footprint. A karve on land is uglier, but a karve on land is a karve that still exists.

Backups that actually work

The minimum viable backup for Valheim is all four files, not just the .db:

worlds_local/
├── MyWorld.db          ← world data (terrain, builds, items)
├── MyWorld.db.old      ← previous save (auto-rotated by game)
├── MyWorld.fwl         ← seed + metadata
└── MyWorld.fwl.old     ← previous metadata

Critical: a .db without its matching .fwl is junk. Back up the full set, always.

Cadence:

Tier	Frequency	Retention
Hot	Hourly	24 hours
Daily	Once a day	30 days
Weekly	Sundays	Indefinite

Game progress lives in the world file, and the cost of storage is trivial compared to losing a long-running save.

Mods on a dedicated server

BepInEx works fine on dedicated servers, but:

• Every connecting client must have a compatible mod loadout. Vanilla clients cannot join a modded server in most cases.
• "Server-side only" mods exist but are rare. Most Valheim mods are content mods that both sides need.
• Mod-related crashes on the server are often silent. Watch the log for "harmony" or "patch" stack traces after restarts.

Practical advice: pin your mod versions. Do not auto-update. Coordinate updates with all players on the same day.

Memory and CPU

Valheim dedicated servers are not heavy. A 4-player server runs comfortably in 2 to 4 GB of RAM. CPU use is moderate, with brief spikes during world generation and combat.

Where the load actually shows up:

• World file I/O on save. A slow disk causes brief tick stutters every save interval.
• Network egress per player. Roughly 5 to 30 KB/s per player, higher during combat or boat travel.

A 4-player Valheim server does not need a beefy host. A 10-player server pushing the engine's ceiling still does not need a beefy host. The constraint is the engine, not the hardware.

A reasonable starter config

For a 4 to 6 player friend group:

• 2 GB RAM allocation
• Modern host with SSD
• Daily backups with 30-day retention
• Modlist pinned in writing somewhere your group can see

For a 8 to 10 player community:

• 4 GB RAM allocation
• Same SSD requirement
• More aggressive backup schedule because more players means more chances to break things

The honest summary

Valheim is one of the lightest-weight games to host. Most hosting problems on Valheim servers come from the game's quirks, not the hosting. Pick any reasonable host, back up religiously, and dock your boats inside walled harbors.