FiresGhettoNetworkMod

Updated for Valheim 1.0.

A comprehensive networking and server-authority mod for Valheim dedicated servers. Combines compression, send-rate tuning, queue management, server-side simulation, RPC filtering, and a per-client auto-tuner into a single drop-in plugin.

What this mod actually does

Valheim's vanilla networking is built around small, friend-group sessions. It works fine for 4 people and starts visibly straining around 8+. This mod replaces the bottlenecks:

• Server pushes harder and smarter, and with more headroom — bigger Steam send/recv buffers, higher max send rates, larger send queues, etc
• Server runs the world authoritatively — server creates/destroys objects for all peers, runs AI, drives spawns, manages zones. Less work on each client.
• Server sends less garbage to clients — filtering on broadcast RPCs, distance-based ZDO update throttling, AI LOD, WearNTear short-circuits for infinite health pieces.
• Client configs are tuned automatically — built-in auto-tuner sends test on first login, picks a performance tier, and applies the right values per machine. No more having to read and understand config values

You don't need to be a networking engineer to run a heavily-modded server with this. That's the point... I'd rather you not touch your configs at all if you dont understand what they do.

What runs in each configuration

The mod is layered. Installing it does not turn everything on — most of the heavy server-authority work sits behind one master switch, and mob simulation sits behind another. Here is exactly what you get.

Server only (vanilla clients)

Everything here is server-side and needs nothing installed on your players' machines:

• Player limit + advertised player limit, crossplay backend selection
• Steam send rate / send buffer, send queue size, ZDO send rate
• Per-peer adaptive send rate (each client ramps toward its own real link capacity)
• Bulk-transfer gate — raises the 20 KB queue limit inside every loaded ServerSync / ServerCharacters copy, so large config syncs on join stop stalling and dropping peers. This is one of the biggest real-world wins and it is entirely server-side
• Server-side auto-tune, plus all diagnostics and admin commands (fgn_headroom, fgn_flood, fgn_socketramp, fgn_comptest, fgn_zdoflood)
• Everything under Server-Side Simulation, if you enable it (see below)

Server + client

Installing on both adds the client-side half:

• ZSTD packet compression — negotiated per peer, so it only engages when both ends have the mod. A vanilla client simply never negotiates and stays uncompressed
• Client-side interpolation and prediction — smooths other players' movement
• Client auto-tune: zone-load batching, instantiation budget, receive-buffer sizing, destroy throttling
• HyperBoost receive side (also needs FiresSteamworksPatcher)

Default settings

Out of the box you get compression, all the send-rate / queue / buffer tuning, adaptive send rate, the bulk-transfer gate, auto-tune, and player-position priority.

Enable Server-Side Simulation is OFF by default, and it is the master gate — while it is off, the RPC router, area-of-interest filtering, AI LOD, ZDO throttling, server-side raids and the ship fixes are all inactive even if their own toggles read true. If you are running a busy server and wondering why those features do not seem to be doing anything, this is why.

Server-Side Simulation ON

Turning on the master switch activates:

• RPC router + area-of-interest filtering — damage numbers, health bars and similar stop being broadcast to everyone and only go to players near the action. This is the big one for large fights
• AI LOD throttling and distance-based ZDO throttling
• ZDO delta compression, WearNTear server CPU skips
• Server-driven spawning and raids / random events
• Extended zone radius and predictive zone streaming, zone create/destroy authority
• Ship steering fixes

Note that mobs are still simulated by the nearest client at this point. The server decides when and where they spawn, and filters the traffic, but it is not running their brains.

ZDO ownership transfer — not recommended

This is the switch that moves creature simulation itself onto the server. Ownership is simulation: whoever owns a creature runs its AI, pathing, attacks, movement physics and death checks. There is a broad variant and a Selective one (creatures, plus ships only if you have also enabled server-side ship physics).

We do not recommend enabling this. It is the least-tested path in the mod, and handing rigidbody simulation to a headless server has knock-on effects — vehicles are the usual casualty. Every other server-authority feature above works without it. If you do want to experiment, use Selective rather than broad, and expect to keep an eye on your boats and carts.

Auto-Tune (the new feature in 1.2.1)

The mod now ships with an auto-tuner that handles config adjustments. Most users should never need to touch a config setting again. (only settings that a client should ever touch will be player sync settings per prefernce)

How the client probe works

When a client connects to a server for the first time, the mod runs a brief network/hardware probe:

1. 30-second delay after spawn — lets Valheim's initial-sync flood drain
2. Hardware fingerprint — CPU cores, RAM, GPU. Scored into a CPU tier.
3. Latency probe — 10 ping RPCs, 200ms apart. performance computed over the trimmed samples (worst outlier dropped). Scores into a network tier.
4. Frame-time sample — 5 seconds of testing afer the world settles. Scores into an FPS tier.
5. Bandwidth probe — 3 × 32KB echo samples, peak wins. Only runs if latency tier is MED or HIGH (this is to keep clients on lower end machines from being effected by the tests).

The result is one of three tiers — LOW, MED, or HIGH — combining hardware capability and link quality. The tier is cached per-server for 7 days; reconnecting picks up where you left off.

How the rolling monitor works

After the initial probe, the mod periodically re-probes latency every 5 minutes. Each result goes into a rolling buffer. This catches:

• Initial probe got unlucky (server happened to be busy) — re-probes will see the truth and promote the tier within 15-20 minutes.
• Mid-session weather changes (ISP route flap, server load) — tier auto-adjusts down or back up as conditions change.

The cache is updated whenever consensus changes, so the next reconnect starts with the corrected tier.

How the server self-tune works

When the mod runs on a dedicated server with Enable Server Auto-Tune = true (the default), the server scores its own CPU/RAM at startup and applies a server-tier preset to:

• ZDO update throttle distance
• AI LOD near/far distances
• RPC Area-of-Interest radius
• Extended zone pre-load radius
• Send queue size
• Steam send buffer size (per-connection outbound during initial sync)

The send-rate Min stays at a safe baseline regardless of server tier so Steam can always back off

The server also collects tier reports from connected clients and periodically logs the median client tier with suggestions, so an admin can see at a glance whether the server's settings actually match the audience joining.

Server-side networking improvements

These run on the dedicated server (the mod auto-detects). Effects are visible to all connected clients regardless of whether they have the mod installed.

Server-authority patches

Vanilla Valheim relies on whichever client is "near" an object to simulate it. This mod makes the server authoritative instead:

• Server creates/destroys objects for all peers — client CPU stays free, world state is consistent across all players.
• Zone management runs server-side — server pre-loads zones around every connected player, including a configurable extended radius (default +1 layer). Smoother zone crossings.
• Server runs all AI — monsters update even when no player is "owning" the zone. Recently adjusted to fix raids not firing with server authority on.
• RPC Router with area based filtering — broadcast RPCs targeting a specific position only forward to peers within range. Massive bandwidth saving on busy servers (DamageText, HealthChanged, SetTarget, etc. don't get broadcast worldwide).

Server authority is server-only behavior. Clients receive the results but don't run the simulation themselves.

Client-side settings (the only ones you should touch you heathens)

If you're a player joining someone else's server, your config has dozens of settings... but the ONLY section relevant to you is Player Sync. Everything else is either server-driven or auto-tuned. If you believe you know best, feel free to adjust, but adjusting settings incorrectly can easily make the mod have the opposite effect from intended...

The Player Sync section has four options:

• Enable Client-Side Interpolation (default: off) Smooths other players' movement on your screen by interpolating between received network positions, eliminating the small snapping that comes from discrete network ticks. Most players don't need this — the rest of the mod's improvements deliver positions smoothly enough on their own, and interpolation adds a small render-lag. Turn ON if you still see other players snap/teleport on a healthy connection.

• Enable Client-Side Prediction (default: off) Extrapolates other players forward using their last known velocity. Helps on high-latency (>100ms) connections where interpolation alone can't cover the gap. Auto-tune may flip this on automatically if your measured ping warrants it. Leave it off otherwise — it can overshoot at low ping.

• Smoothing Min Interval (default: 0.0s) Below this inter-packet arrival rate, smoothing is disabled and vanilla movement renders directly. 0 means "always smooth"; raise it only on LAN/very low-latency servers if you want fast packets to bypass smoothing.

• Smoothing Max Interval (default: 0.20s) Above this inter-packet arrival rate, smoothing runs at full strength. Between Min and Max the strength fades in linearly. Raise for a more aggressive fade (less smoothing on borderline connections); lower for a snappier ramp to full smoothing.

Everything else in the config is either server-only or auto-tuned. The mod automatically disables server-only features on clients regardless of what you set. so that you can't manually toggle Enable Server-Side Simulation on your client, but im not smart enough to know how to hide the config to only clients while allowing admins and servers to see it.

Installation

1. Install BepInEx (a recent BepInExPack_Valheim from Thunderstore is recommended).
2. Drop VAGhettoNetworking.dll into BepInEx/plugins/ on every machine that should have it.
3. Start Valheim or your dedicated server. The mod auto-detects which side it's running on and enables the appropriate features.

Compatibility

• Designed to coexist with many mods, I use it on my own server with 60 other mods, and have tested it with many others
• Works alongside any content mods that don't touch ZNetScene/ZDOMan internals. (doesn't work with most other networking mods, besides better z log and timeout limits, both highly recommended to go with this)
• If you also run BetterNetworking, Serverside Simulations, or another networking mod — disable one. Running two networking mods at once will produce conflicting patches. This mod covers what those two do.

Credits

Built on the shoulders of BetterNetworking and Serverside Simulations. The general approach to ZDO throttling, RPC routing/AoI filtering, and ZSTD wire compression took inspiration from those mods and from the Comfy Valheim BetterZeeRouter pattern. The auto-tuner, rolling monitor, server self-tune, and Steam send-buffer tuning are original to this mod as far as I know... but theres only so many different ways to do networking mods in valheim

License: see LICENSE in the repo.

Issues / questions

https://discord.gg/zQRgHbqms4

• v1.4.0 - updated for Valheim 1.0

• v1.3.16 - pens, boats, and an honest toggle

  • Tamed and trapped creatures stay put. Leaving an area tore the world down over several frames, so a creature could outlive the walls around it, wander out through the gap, and have that escaped position saved. Anything that can move is now removed in the same frame vanilla removes it, and containment is destroyed last.
  • Boats no longer take damage on calm water. A server that owned a hull applied no buoyancy until that zone's water finished loading but left gravity running, so empty ships sank into the seabed and damaged themselves on landing. Server-owned hulls now hold still until their surroundings actually exist.
  • "Server-Side Ship Simulation" now does what it says. It was never wired to anything, so switching on ZDO ownership quietly handed ship physics to the server even with that setting off. Ships stay client-simulated unless you deliberately opt in.
  • Creatures are placed where the world says they are before the server's first physics step after it takes ownership, rather than one step afterwards.
  • Added diagnostics so the fixes report what they actually did: teardown now logs how many moving objects it removed in-frame, and a parked ship logs how long it waited for its surroundings to load.

• v1.3.11 - maintenance and fixes

• v1.3.10 dedicated-server terrain fix (world pre-gen, Upgrade World resets, crops)

  • Fixed a null-reference error flood on dedicated servers during bulk world pre-generation when using server authority

• v1.3.9 stuck-raid fix for dedicated servers

  • Fixed raids / random events that could run forever on a dedicated server — mobs chasing players "for days," only stopping if FGN was removed. With no local player standing at the event origin, vanilla pauses the event timer the moment every player leaves the area, so the raid never reaches its end time — while FGN keeps spawning its event mobs around whoever is online. The timer now runs on wall-clock regardless of who is in the area, so raids end at their authored duration, with a 1-hour hard failsafe that force-ends any event that somehow outlives it.
  • Internal networking pass (per-packet compression negotiation, bulk-transfer gate, auto-tune probe). No config changes.

• v1.3.8 crossplay default fix + per-peer adaptive send rate

  • Crossplay servers could fail to connect after installing FGN. "Force Crossplay" now defaults to "vanilla"
  • Per-peer adaptive send rate — each client now ramps from the auto-tune baseline up toward its own real link capacity
  • Auto-tune HIGH send ceiling raised (~8 -> ~32 MB/s) with a larger send buffer and queue, so a healthy link isn't artificially throttled.
  • HYPERBOOST toggle — one-switch max-throughput override (Steam send/recv rates + buffers) for benchmarking or high-bandwidth links. Default off; pinning everything wide open really isn't a great idea, but if you really want to, have at it (requires fires steamworks patcher on client as well as server)
  • Patcher-dependent settings (the recv-buffer tuning, including HyperBoost's recv side)
  • Crops should now grow correctly under server-side simulation
  • Plays nice with Render Limits now — if Jere's Render Limits is installed, FGN stops stacking its extended zone radius on top and lets Render Limits own the zone load distances (server authority stays intact)

• v1.3.7 disconnect + fall-through + steamworks-limit fixes

  • Clients no longer choke on default Steam bandwidth limits during big transfers.
  • The bandwidth lift now applies through other mods' socket wrappers instead of getting lost.
  • Fixed a compression bug that caused "Disconnected" drops on busy servers.
  • Items and graves stay put until the floor under them finishes loading instead of falling through.
  • Fall-through diagnostic logging is now off by default behind a toggle.

• v1.3.6 tombstone/tames fix

  • graves and tames should stop dropping through structures on zone reload

• v1.3.5 auto-tune adjustment

  • a strong PC on a high-ping connection no longer gets dropped to low settings. your hardware sets the ceiling, a bad connection only nudges it down a step
  • player smoothing/prediction are left to the clients preferences again, auto-tune doesn't force them on

• v1.3.4 stability pass for big/busy servers

  • smoother on rented/shared hosts, now TRYING to read the actual server box specs not the hosts specs
  • "Update Rate" renamed to "ZDO Send Rate"
  • better disconnect logging to track down any hiccups

• v1.3.3 multi-player area fixes + permission-mod compat

  • players flying / hits from across the map fixed. BulkTransferGuard was the cause, replaced with BulkTransferGate (raises ServerSync send queue gate at the source instead of suppressing ZDOMan.SendZDOs)
  • delta compression self-heals now — full vanilla keyframe every 5s per peer/zdo so a dropped packet doesn't desync fields forever
  • RPC router stopped wasting cycles forwarding server-targeted RPCs to itself
  • IsActiveAreaLoaded gate uses vanilla active-area only, megabases stop choking on it
  • ported SSS defensive trio (humanoid null guard, WNT collider re-init, ship request-handoff)
  • CreateDestroyObjects NRE prune. fires when permission mods like TargetPortalProtection block portal destroy on the dedi and leave m_instances out of sync
  • broad server ownership auto-skips portals when TargetPortalProtection is installed
  • misc log + diagnostic tidy

• v1.3.2 realized the error of my ways

  • compat with serversync send limits
  • added experimental server ownership toggles... basically ports the rest of server simulations. off by default

• v1.3.1 fixes for compression conflicts with SC

• v1.3.0 server + bandwidth performance pass:

  • ZDO delta compression — server only re-sends ZDO fields that changed (wire-compatible with vanilla)
  • Server-side WearNTear skip — UpdateWear short-circuits for stable / invulnerable pieces
  • Client-side support skip — invulnerable pieces stop running UpdateSupport, max-support pinned at Awake
  • Shared invulnerability classifier — Immune + Ignore both treated as zero-damage
  • AoI-filtered SpawnedZone rebroadcast — server-side rebroadcast bound by AoI radius instead of all-peers
  • Public-test build gating — ready for live valheim updates
  • Internal reorg —

• v1.2.1 per-client Auto-Tune system added:

  • Network/hardware probe runs on first login (latency, jitter, frame time, bandwidth, hardware fingerprint), picks a LOW/MED/HIGH tier, applies tier-appropriate settings automatically
  • Two-axis tier scoring (machine vs link) — strong client on a clean-latency link no longer dragged down by server-bottlenecked bandwidth measurements
  • Rolling monitor re-probes every 5 minutes after initial probe; tier auto-corrects if conditions change mid-session or initial probe was contaminated by startup traffic
  • Server self-tune scores host CPU/RAM and applies tier presets to ZDO throttle / AI LOD / RPC AoI / queue size / extended zone radius / Steam buffers (default ON)
  • Per-server cache (7-day TTL, hardware-fingerprint-aware) so reconnecting picks up the established tier
  • Steam SendBufferSize wired up (per-connection outbound buffer, up to 2MB) — addresses k_EResultLimitExceeded errors during initial-sync floods
  • Asymmetric send-rate pattern (Min stays at safe baseline, Max scales with tier) — no risk of pushing a slow client harder than they can handle
  • ZoneLoadBatchSize (formerly stubbed) now wired into ZNetScene's per-frame creation cap via runtime helper; HIGH-tier clients consume zone backlog 4x faster
  • ZPackage Receive Buffer config bound and applied (no-op on Valheim's bundled Steamworks build but ready when SDK updates)
  • Default Enable Server Auto-Tune flipped ON (was OFF in 1.2.0)
  • Default Enable Client-Side Interpolation flipped OFF (was ON before — the rest of the networking improvements deliver smooth positions on their own; turn back ON if you still see snap/teleport)
  • README rewritten with proper documentation of features, auto-tune, server-authority patches, and the four client-side knobs that are the only settings users should ever touch

• v1.2.0 removed log snapshots beta, will have to become its own mod someday soon

• v1.1.9 adjustments to player positioning patches as well as default config settings, added a new beta feature for login snapshots as well

• v1.1.8 better client position handling for players with higher ping differences (only works when installed on server and client)

• v1.1.7 various tweaks and a bug fix for accidentally hiding the player-player poistion sync in configs

• v1.1.6 better server checking for renamed assemblys

• v1.1.5 fixes to server authority ai patches. improved performance, stopped causing issues with interactions and monsters...

• v1.1.1 fixed single player running logic as dedicated server and spamming errors finally

• v1.1.0 compatibility updates

• v1.0.2 update for not playing well with wackies db