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 can run the world — with Server-Side Simulation on, the server loads the world around every player, drives spawns and raids, and manages zones
• Server sends less garbage and does less busywork — filtering on broadcast RPCs, closest-first ZDO sending when a connection backs up, AI LOD, WearNTear skips for unbreakable 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:

• Deflate 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)
• Boat damage fix — every 2 seconds the server corrects each player's clock, and vanilla jumps the waves to match, which a boat with players aboard takes as slamming into the water. The mod eases those corrections in so the water never jumps. A ship is damaged by the game of whoever owns it (normally someone aboard), so every player who sails needs the mod

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. A dedicated server also gets these traffic features, each behind its own toggle:

• 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
• ZDO delta compression and distance-based ZDO throttling
• AI LOD throttling and WearNTear server CPU skips. These only act on objects the server itself has loaded, so they have little to do unless Server-Side Simulation is on

Enable Server-Side Simulation is OFF by default. It only controls the server simulating the world. The traffic features above follow their own toggles whether it is on or off.

Server-Side Simulation ON

Turning on the master switch activates:

• 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.

With ValheimCommunityPatch on the server, Server-Side Simulation stays off for that session and the server log says why. VCP replaces the server's object create/destroy pass with its own, built around the world origin, and removes everything the server creates for players, so the two would fight endlessly. The traffic features above keep working either way.

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 × 128KB 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:

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

Every tier stays at or above vanilla's values; the startup log confirms it with AutoTune VanillaFloor self-check passed.

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. With Server-Side Simulation on, the server takes over more of that work:

• Server loads the world around every player — objects exist on the server wherever players are, including a configurable extended radius (default +1 zone layer).
• Spawning and raids run server-side — the server decides when and where creatures and random events spawn, so raids fire and end properly with players spread out.
• Creatures go to the best-placed player - the server measures each player's round trip and moves a creature to whoever is fighting it, or to a nearby player with clearly lower ping, so its movement, attacks and the hits on it are worked out on the machine best placed to do it. The current owner's game hands the creature over itself, the way vanilla hands over a chest someone opens, so no update already in flight can undo the move. Bosses, tames, ridden creatures and creatures mid-attack are never moved, and only players who also have the mod can hand one over. ZDO ownership transfer (see "What runs in each configuration") is a separate, heavier option.

The RPC Router with area based filtering does not need Server-Side Simulation: 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).

All of this is server-side; players don't need anything extra installed for it.

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.
• ValheimCommunityPatch works alongside it: where both do the same job, this mod stands down and lets VCP handle it (see Server-Side Simulation ON above).

Credits

Built on the shoulders of BetterNetworking and Serverside Simulations. The general approach to ZDO throttling, RPC routing/AoI filtering, and 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