NetworkPerformanceSystem

Network Performance Systems is a general networking overhaul, designed to tackle the problem created by high ping.

In Valheim, most objects are simulated by users. So a single high ping user in an area can make everything or all sorts of things feel terrible. This mod aims to address that in a number of ways.

Why this is different from the other networking mods

Every other Valheim networking mod treats multiplayer performance as a bandwidth problem — compression, bigger buffers, higher send rates, filtered broadcasts. That is the right diagnosis for ten people in one base saturating a shared cap. It does not handle a larger distributed server, or multiple players from vastly different goegraphic locations.

NPS addresses these issues in a number of ways

Each peer gets their own Round Trip timing (RTT), Healthcheck and bandwidth estimates
- This allows dynamic adjustments to route around a poor connection
- This higher ping players with decent bandwidth allow the server to send more aggressively to these players in compensation
- Object ownership can be dynamically adjusted around players with poor connections to provide the best experience for all players in the area
Objects which need network calls to interact with get ownership transferred ahead of time, delay scenarios much less likely
Objects that change ownership during active requests get their requests properly re-targeted against the new owner
Objects which are locally important (footsteps for example) are only network broadcast locally, instead of globally around the server
Server Garbage collection churn is significantly reduced compared to vanilla

Installing

Server-only works. Vanilla clients get the send window, ownership, scheduler, station-request and creature-hit fixes with nothing installed on their end, and the server follows where they actually are rather than where they were two seconds ago.

Installing on clients too adds latency compensation, live position reporting and the clean exit from a dead session for those clients, and lets a ship they own pass to whoever takes its helm. Mixed groups are fine — benefits are per-player, and a client without the mod behaves exactly as vanilla. There is no version lock: nobody gets kicked for not having it.

Works on dedicated servers and on player-hosted games.

Diagnosing and Reporting a problem

An easy way to start is enabling the nps_stats display Run nps_stats_collect (needs devcommands, since sampling costs a Steam call per peer per tick), play, then nps_stats.

A player the link-pressure table marks as LOSSY is already being dealt with: the server steps that one player's send rate down until their connection stops losing packets, and back up once it is clean, without changing anyone else's rate (Steam Transport / Enable Loss Backoff). The "Loss backoff" block shows who is backed off and by how much.

Lag, rubber-banding, hits not landing? Send a report.

Server owners: in BepInEx/config/MidnightsFX.NetworkPerformanceSystem.cfg, set Enable Network Monitoring = true under [Monitoring]. You do not need to restart, and an admin can also change it in game. Play through the problem, set it back to false, and zip the newest folder in BepInEx/NpsMonitoring/.

Players: your game sends nothing unless the server asks, and never sends names, platform ids, addresses or chat. To opt out anyway, set AllowMonitoringUpload = false under [Client config] in your own copy of that file. The server cannot override it. It only stops your game uploading: the server still logs its own side of the connection, such as your ping, under an anonymous session number.

Then post the zip as a GitHub issue or on the Discord, with a description of what you saw: what happened, how often, roughly when, and how many players were on. See Reporting a network problem for what is recorded.

If creatures rubber-band, hits do nothing, or things freeze when players come and go, the server can record what the network was doing so it can be diagnosed rather than guessed at.

On the server, set Enable Network Monitoring to true in the Monitoring section. No restart is needed, and it can be changed in game by an admin.
Play through the problem. An evening with the usual players is ideal.
Set it back to false.
Zip the newest folder under BepInEx/NpsMonitoring/ on the server and send it, with a sentence about what players saw and roughly when, as a GitHub issue or on the Discord.

What is recorded: each time a creature changes owner and whether the change held, messages delivered to a player who no longer owned the target, how regularly each player's creatures report in, and each player's ping and connection quality once a second. Clients that have the mod add what only they can see: what a creature was doing when it changed hands, who it was fighting, how far it jumped on screen, and frame rate. That costs each client up to 2 KB per second of upload, sent in small batches that are held back whenever the connection is busy with the game's own traffic, so recording never delays it.

What is not: player names, Steam or platform ids, IP addresses, chat. Players appear only as the random session number the game gives them for that connection, and positions are rounded to the metre. Any player can refuse to send anything by setting AllowMonitoringUpload to false in their own config.

While it is off it costs nothing: the hooks it uses are only installed while it is on. The folder is capped by Max Disk MB (4096 by default, across all sessions). When the cap is reached recording stops and the log says so; nothing already recorded is deleted, so clear out old sessions yourself. nps_stats shows whether it is running and whether anything is being dropped.

Incompatible with

Other networking mods that rewrite the same code: FiresGhettoNetworking, VBNetTweaks, SkadiNet, BetterNetworking, Smoothbrain's Network, NetworkTweaks, WarheimNetwork, TimeoutLimit. BepInEx will refuse to load this mod alongside them rather than leave you half-patched. TimeoutLimit in particular is no longer something you give up: the Connection Timeout settings cover the same ground, and unlike a timeout raised at one layer only, they move both of the places vanilla times out at.

Verified compatible (different layers, no overlap): LeanNet, Compress, Scenic. ReturnToSender is fine too — it already fixes the scheduler, so that one mechanism stands down and the rest keeps working. EnRoute and BetterZeeRouter are fine in the same way: both rework the routed-RPC relay, so relay filtering and relay send reuse stand down when either is present and everything else keeps working. Valheim Plus is fine too: it has its own player limit, so this mod's Player Limit settings are ignored when it is installed and V+'s maxPlayers is the one in force. ClientGhostWatchdog is fine as well: it does the client-side half of the ghost handling itself and against its own timeout, so this mod's client watchdog stands down and leaves that mod's behaviour in charge. The host-side half — evicting a ghost from ownership, which that mod does not do — keeps running either way.

Credits

Disconnect ghosting from ClientGhostWatchdog by DreamWraith.
ZDO Redirect from BetterZeeRouter