'Network protocol error' for all players when multiple player are connected at same time

[EnderNon]

I set this server up using MCHPRS and Velocity. I have ViaVersion plugin on Velocity so that I can use 1.21 for a certain mod that only supports 1.21. My issue is that, with one player, I can join. When my friend joins to test it, both of us get kicked with a "Network protcol error" and something about a zombie villager. Not sure why that's happening.

For reference, MCHRPS is at 127.0.0.1:25565 and Velocity is facing outwards at 0.0.0.0:25566. Both of us are connecting directly via (ipv4Address):25566.

Error log

---- Minecraft Network Protocol Error Report ----
// I'm sorry, I don't speak that language

Time: 2024-12-14 21:44:40
Description: Packet handling error

java.lang.IllegalStateException: Invalid entity data item type for field 17 on entity class_1641['Zombie Villager'/1, l='ClientLevel', x=125.28, y=8.66, z=129.02]: old=0(class java.lang.Integer), new=127(class java.lang.Byte)
	at knot//net.minecraft.class_2945.method_12785(class_2945.java:126)
	at knot//net.minecraft.class_2945.method_12779(class_2945.java:117)
	at knot//net.minecraft.class_634.method_11093(class_634.java:553)
	at knot//net.minecraft.class_2739.method_11808(class_2739.java:54)
	at knot//net.minecraft.class_2739.method_11054(class_2739.java:12)
	at knot//net.minecraft.class_2600.method_11072(class_2600.java:27)
	at knot//net.minecraft.class_1255.method_18859(class_1255.java:162)
	at knot//net.minecraft.class_4093.method_18859(class_4093.java:23)
	at knot//net.minecraft.class_1255.method_16075(class_1255.java:136)
	at knot//net.minecraft.class_1255.method_5383(class_1255.java:121)
	at knot//net.minecraft.class_310.method_1523(class_310.java:1240)
	at knot//net.minecraft.class_310.method_1514(class_310.java:882)
	at knot//net.minecraft.client.main.Main.main(Main.java:256)
	at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:480)
	at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74)
	at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
	at org.prismlauncher.launcher.impl.StandardLauncher.launch(StandardLauncher.java:105)
	at org.prismlauncher.EntryPoint.listen(EntryPoint.java:129)
	at org.prismlauncher.EntryPoint.main(EntryPoint.java:70)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Render thread
Stacktrace:
	at knot//net.minecraft.class_2945.method_12785(class_2945.java:126)
	at knot//net.minecraft.class_2945.method_12779(class_2945.java:117)

-- Incoming Packet --
Details:
	Type: clientbound/minecraft:set_entity_data
	Is Terminal: false
	Is Skippable: false
Stacktrace:
	at knot//net.minecraft.class_2600.method_59803(class_2600.java:56)
	at knot//net.minecraft.class_8673.method_60882(class_8673.java:136)
	at knot//net.minecraft.class_8673.method_59807(class_8673.java:113)
	at knot//net.minecraft.class_2600.method_11072(class_2600.java:32)
	at knot//net.minecraft.class_1255.method_18859(class_1255.java:162)
	at knot//net.minecraft.class_4093.method_18859(class_4093.java:23)
	at knot//net.minecraft.class_1255.method_16075(class_1255.java:136)
	at knot//net.minecraft.class_1255.method_5383(class_1255.java:121)
	at knot//net.minecraft.class_310.method_1523(class_310.java:1240)
	at knot//net.minecraft.class_310.method_1514(class_310.java:882)
	at knot//net.minecraft.client.main.Main.main(Main.java:256)
	at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:480)
	at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74)
	at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
	at org.prismlauncher.launcher.impl.StandardLauncher.launch(StandardLauncher.java:105)
	at org.prismlauncher.EntryPoint.listen(EntryPoint.java:129)
	at org.prismlauncher.EntryPoint.main(EntryPoint.java:70)

-- Connection --
Details:
	Protocol: play
	Flow: CLIENTBOUND
	Server type: OTHER
	Server brand: Minecraft High Performance Redstone (Velocity)


-- System Details --
Details:
	Minecraft Version: 1.21.1
	Minecraft Version ID: 1.21.1
	Operating System: Linux (amd64) version 6.12.4-zen1-1-zen
	Java Version: 21.0.3, Eclipse Adoptium
	Java VM Version: OpenJDK 64-Bit Server VM (mixed mode, sharing), Eclipse Adoptium
	Memory: 3868540752 bytes (3689 MiB) / 5117050880 bytes (4880 MiB) up to 17179869184 bytes (16384 MiB)
	CPUs: 20
	Processor Vendor: GenuineIntel
	Processor Name: 13th Gen Intel(R) Core(TM) i5-13500
	Identifier: Intel64 Family 6 Model 191 Stepping 2
	Microarchitecture: unknown
	Frequency (GHz): -0.00
	Number of physical packages: 1
	Number of physical CPUs: 14
	Number of logical CPUs: 20
	Graphics card #0 name: AD106 [GeForce RTX 4060 Ti]
	Graphics card #0 vendor: NVIDIA Corporation (0x10de)
	Graphics card #0 VRAM (MiB): 8224.00
	Graphics card #0 deviceId: 0x2803
	Graphics card #0 versionInfo: unknown
	Virtual memory max (MiB): 28220.83
	Virtual memory used (MiB): 15001.61
	Swap memory total (MiB): 12287.99
	Swap memory used (MiB): 27.36
	Space in storage for jna.tmpdir (MiB): <path not set>
	Space in storage for org.lwjgl.system.SharedLibraryExtractPath (MiB): <path not set>
	Space in storage for io.netty.native.workdir (MiB): <path not set>
	Space in storage for java.io.tmpdir (MiB): available: 15893.34, total: 15932.84
	Space in storage for workdir (MiB): available: 269765.50, total: 642514.00
	JVM Flags: 2 total; -Xms512m -Xmx16384m
	Fabric Mods: 
		architectury: Architectury 13.0.8
		betterf3: BetterF3 11.0.3
		bsvsb: Better Sodium Video Settings Button 4.0.0-alpha.0
		clearview: clearview 1.0.0
			midnightlib: MidnightLib 1.6.4
		cloth-config: Cloth Config v15 15.0.140
			cloth-basic-math: cloth-basic-math 0.6.1
		continuity: Continuity 3.0.0+1.21
		cullleaves: Cull Leaves 3.4.0
		debugify: Debugify 1.21.1+1.0
		dynamic_fps: Dynamic FPS 3.7.7
			net_lostluma_battery: battery 1.3.0
		enhancedblockentities: Enhanced Block Entities 0.10.2+1.21
		entity_model_features: Entity Model Features 2.2.6
		entity_texture_features: Entity Texture Features 6.2.8
			org_apache_httpcomponents_httpmime: httpmime 4.5.10
		entityculling: EntityCulling 1.7.2
		fabric-api: Fabric API 0.110.0+1.21.1
			fabric-api-base: Fabric API Base 0.4.42+6573ed8c19
			fabric-api-lookup-api-v1: Fabric API Lookup API (v1) 1.6.70+b559734419
			fabric-biome-api-v1: Fabric Biome API (v1) 13.0.30+be1ed2d719
			fabric-block-api-v1: Fabric Block API (v1) 1.0.22+0af3f5a719
			fabric-block-view-api-v2: Fabric BlockView API (v2) 1.0.10+6573ed8c19
			fabric-blockrenderlayer-v1: Fabric BlockRenderLayer Registration (v1) 1.1.52+0af3f5a719
			fabric-client-tags-api-v1: Fabric Client Tags 1.1.15+6573ed8c19
			fabric-command-api-v1: Fabric Command API (v1) 1.2.49+f71b366f19
			fabric-command-api-v2: Fabric Command API (v2) 2.2.28+6ced4dd919
			fabric-commands-v0: Fabric Commands (v0) 0.2.66+df3654b319
			fabric-content-registries-v0: Fabric Content Registries (v0) 8.0.18+b559734419
			fabric-convention-tags-v1: Fabric Convention Tags 2.1.2+7f945d5b19
			fabric-convention-tags-v2: Fabric Convention Tags (v2) 2.9.2+e60e56d419
			fabric-crash-report-info-v1: Fabric Crash Report Info (v1) 0.2.29+0af3f5a719
			fabric-data-attachment-api-v1: Fabric Data Attachment API (v1) 1.4.0+da19b51a19
			fabric-data-generation-api-v1: Fabric Data Generation API (v1) 20.2.24+16c4ae2519
			fabric-dimensions-v1: Fabric Dimensions API (v1) 4.0.0+6fc22b9919
			fabric-entity-events-v1: Fabric Entity Events (v1) 1.7.0+2122d82819
			fabric-events-interaction-v0: Fabric Events Interaction (v0) 0.7.13+ba9dae0619
			fabric-game-rule-api-v1: Fabric Game Rule API (v1) 1.0.53+6ced4dd919
			fabric-item-api-v1: Fabric Item API (v1) 11.1.1+d5debaed19
			fabric-item-group-api-v1: Fabric Item Group API (v1) 4.1.6+6823f7cd19
			fabric-key-binding-api-v1: Fabric Key Binding API (v1) 1.0.47+0af3f5a719
			fabric-keybindings-v0: Fabric Key Bindings (v0) 0.2.45+df3654b319
			fabric-lifecycle-events-v1: Fabric Lifecycle Events (v1) 2.5.0+01d9a51c19
			fabric-loot-api-v2: Fabric Loot API (v2) 3.0.15+3f89f5a519
			fabric-loot-api-v3: Fabric Loot API (v3) 1.0.3+3f89f5a519
			fabric-message-api-v1: Fabric Message API (v1) 6.0.13+6573ed8c19
			fabric-model-loading-api-v1: Fabric Model Loading API (v1) 2.0.0+fe474d6b19
			fabric-networking-api-v1: Fabric Networking API (v1) 4.3.0+c7469b2119
			fabric-object-builder-api-v1: Fabric Object Builder API (v1) 15.2.1+40875a9319
			fabric-particles-v1: Fabric Particles (v1) 4.0.2+6573ed8c19
			fabric-recipe-api-v1: Fabric Recipe API (v1) 5.0.13+6508971219
			fabric-registry-sync-v0: Fabric Registry Sync (v0) 5.2.0+34f5d91419
			fabric-renderer-api-v1: Fabric Renderer API (v1) 3.4.0+c705a49c19
			fabric-renderer-indigo: Fabric Renderer - Indigo 1.7.0+c705a49c19
			fabric-renderer-registries-v1: Fabric Renderer Registries (v1) 3.2.68+df3654b319
			fabric-rendering-data-attachment-v1: Fabric Rendering Data Attachment (v1) 0.3.48+73761d2e19
			fabric-rendering-fluids-v1: Fabric Rendering Fluids (v1) 3.1.6+1daea21519
			fabric-rendering-v0: Fabric Rendering (v0) 1.1.71+df3654b319
			fabric-rendering-v1: Fabric Rendering (v1) 5.0.5+df16efd019
			fabric-resource-conditions-api-v1: Fabric Resource Conditions API (v1) 4.3.0+8dc279b119
			fabric-resource-loader-v0: Fabric Resource Loader (v0) 1.3.1+5b5275af19
			fabric-screen-api-v1: Fabric Screen API (v1) 2.0.25+8b68f1c719
			fabric-screen-handler-api-v1: Fabric Screen Handler API (v1) 1.3.88+b559734419
			fabric-sound-api-v1: Fabric Sound API (v1) 1.0.23+6573ed8c19
			fabric-transfer-api-v1: Fabric Transfer API (v1) 5.4.2+95bead5f19
			fabric-transitive-access-wideners-v1: Fabric Transitive Access Wideners (v1) 6.2.0+45b9699719
		fabric-language-kotlin: Fabric Language Kotlin 1.13.0+kotlin.2.1.0
			org_jetbrains_kotlin_kotlin-reflect: kotlin-reflect 2.1.0
			org_jetbrains_kotlin_kotlin-stdlib: kotlin-stdlib 2.1.0
			org_jetbrains_kotlin_kotlin-stdlib-jdk7: kotlin-stdlib-jdk7 2.1.0
			org_jetbrains_kotlin_kotlin-stdlib-jdk8: kotlin-stdlib-jdk8 2.1.0
			org_jetbrains_kotlinx_atomicfu-jvm: atomicfu-jvm 0.26.1
			org_jetbrains_kotlinx_kotlinx-coroutines-core-jvm: kotlinx-coroutines-core-jvm 1.9.0
			org_jetbrains_kotlinx_kotlinx-coroutines-jdk8: kotlinx-coroutines-jdk8 1.9.0
			org_jetbrains_kotlinx_kotlinx-datetime-jvm: kotlinx-datetime-jvm 0.6.1
			org_jetbrains_kotlinx_kotlinx-io-bytestring-jvm: kotlinx-io-bytestring-jvm 0.6.0
			org_jetbrains_kotlinx_kotlinx-io-core-jvm: kotlinx-io-core-jvm 0.6.0
			org_jetbrains_kotlinx_kotlinx-serialization-cbor-jvm: kotlinx-serialization-cbor-jvm 1.7.3
			org_jetbrains_kotlinx_kotlinx-serialization-core-jvm: kotlinx-serialization-core-jvm 1.7.3
			org_jetbrains_kotlinx_kotlinx-serialization-json-jvm: kotlinx-serialization-json-jvm 1.7.3
		fabricloader: Fabric Loader 0.16.9
			mixinextras: MixinExtras 0.4.1
		fallingleaves: Falling Leaves 1.16.4
		ferritecore: FerriteCore 7.0.2-hotfix
		forgeconfigapiport: Forge Config API Port 21.1.2
			com_electronwill_night-config_core: core 3.8.0
			com_electronwill_night-config_toml: toml 3.8.0
		fzzy_config: Fzzy Config 0.5.9+1.21
			blue_endless_jankson: jankson 1.2.3
			fabric-permissions-api-v0: fabric-permissions-api 0.3.1
			net_peanuuutz_tomlkt_tomlkt-jvm: tomlkt-jvm 0.3.7
		immediatelyfast: ImmediatelyFast 1.3.3+1.21.1
			net_lenni0451_reflect: Reflect 1.3.4
		inhibitor: Inhibitor 1.0.1
		iris: Iris 1.8.1+mc1.21.1
			io_github_douira_glsl-transformer: glsl-transformer 2.0.1
			org_anarres_jcpp: jcpp 1.4.14
			org_antlr_antlr4-runtime: antlr4-runtime 4.13.1
		isiwiw: I shall install whatever I want 1.2+fabric-1.21
		java: OpenJDK 64-Bit Server VM 21
		lambdynlights: LambDynamicLights 3.1.4+1.21.1
			pride: Pride Lib 1.2.1+1.21
			spruceui: SpruceUI 5.1.0+1.21
		languagereload: Language Reload 1.7.1+1.21.1
		lithium: Lithium 0.14.3-snapshot+mc1.21.1-build.92
		minecraft: Minecraft 1.21.1
		modmenu: Mod Menu 11.0.3
		morechathistory: More Chat History 1.3.1
		moreculling: More Culling 1.0.1
			conditional-mixin: conditional mixin 0.6.3
			mixinsquared: MixinSquared 0.2.0
		no-telemetry: No Telemetry 1.8.0
		nochatreports: No Chat Reports 1.21.1-v2.9.1
		noxesium: Noxesium 2.3.3+d22848f
			com_noxcrew_noxesium_api: api 2.3.3+d22848f
			org_khelekore_prtree: prtree 1.5
		particle_core: Particle Core 0.2.4+1.21
		placeholder-api: Placeholder API 2.4.1+1.21
		reeses-sodium-options: Reese's Sodium Options 1.8.0+mc1.21.3
		skinlayers3d: 3d-Skin-Layers 1.7.3
		sodium: Sodium 0.6.3+mc1.21.1
		sodium-extra: Sodium Extra 0.6.0+mc1.21.1
		sodiumextrainformation: Sodium Extra Information 2.3
		sodiumextras: Sodium Extras 1.0.5
		sodiumleafculling: Sodium Leaf Culling 1.0.0
		sodiumoptionsapi: Sodium Options API 1.0.8
		sound_physics_remastered: Sound Physics Remastered 1.21.1-1.4.6
		sspb: Sodium Shadowy Path Blocks 4.0.0
		tcdcommons: TCD Commons API 3.12.4+fabric-1.21
		visiblebarriers: Visible Barriers 2.0.16
		vmp: Very Many Players 0.2.0+beta.7.169+1.21.1
			com_ibm_async_asyncutil: asyncutil 0.1.0
		wynntils: Wynntils 2.4.7
		yet_another_config_lib_v3: YetAnotherConfigLib 3.6.2+1.21-fabric
			com_twelvemonkeys_common_common-image: common-image 3.12.0
			com_twelvemonkeys_common_common-io: common-io 3.12.0
			com_twelvemonkeys_common_common-lang: common-lang 3.12.0
			com_twelvemonkeys_imageio_imageio-core: imageio-core 3.12.0
			com_twelvemonkeys_imageio_imageio-metadata: imageio-metadata 3.12.0
			com_twelvemonkeys_imageio_imageio-webp: imageio-webp 3.12.0
			org_quiltmc_parsers_gson: gson 0.2.1
			org_quiltmc_parsers_json: json 0.2.1
		zoomify: Zoomify 2.14.2+1.21.1
			com_akuleshov7_ktoml-core-jvm: ktoml-core-jvm 0.5.2
	Loaded Shaderpack: (off)

configurations.

MCHPRS config file

Config.toml
bind_address = "127.0.0.1:25565"
motd = "testing redstone server fr"
chat_format = "{username}: {message}"
max_players = 64
view_distance = 8
whitelist = false
schemati = false
block_in_hitbox = true
auto_redpiler = true

[velocity]
enabled = true
# This is the secret contained within `forwarding-secret-file` from your velocity config,
# NOT the path to the file.
secret = "THIS IS CENSORED"

Velocity config file

velocity.toml
# Config version. Do not change this
config-version = "2.7"

# What port should the proxy be bound to? By default, we'll bind to all addresses on port 25565.
bind = "0.0.0.0:25566"

# What should be the MOTD? This gets displayed when the player adds your server to
# their server list. Only MiniMessage format is accepted.
motd = "<obfuscated><color:#7F00FF>fr</color></obfuscated> frfrnocap redstone testing grounds <obfuscated><color:#7F00FF>fr</color></obfuscated>\n<obfuscated><color:#7F00FF>no</color></obfuscated>   Incomprehensible stuffs inbound    <obfuscated><color:#7F00FF>cp</color></obfuscated>"

# What should we display for the maximum number of players? (Velocity does not support a cap
# on the number of players online.)
show-max-players = 64

# Should we authenticate players with Mojang? By default, this is on.
online-mode = true

# Should the proxy enforce the new public key security standard? By default, this is on.
force-key-authentication = true

# If client's ISP/AS sent from this proxy is different from the one from Mojang's
# authentication server, the player is kicked. This disallows some VPN and proxy
# connections but is a weak form of protection.
prevent-client-proxy-connections = false

# Should we forward IP addresses and other data to backend servers?
# Available options:
# - "none":        No forwarding will be done. All players will appear to be connecting
#                  from the proxy and will have offline-mode UUIDs.
# - "legacy":      Forward player IPs and UUIDs in a BungeeCord-compatible format. Use this
#                  if you run servers using Minecraft 1.12 or lower.
# - "bungeeguard": Forward player IPs and UUIDs in a format supported by the BungeeGuard
#                  plugin. Use this if you run servers using Minecraft 1.12 or lower, and are
#                  unable to implement network level firewalling (on a shared host).
# - "modern":      Forward player IPs and UUIDs as part of the login process using
#                  Velocity's native forwarding. Only applicable for Minecraft 1.13 or higher.
player-info-forwarding-mode = "modern"

# If you are using modern or BungeeGuard IP forwarding, configure a file that contains a unique secret here.
# The file is expected to be UTF-8 encoded and not empty.
forwarding-secret-file = "forwarding.secret"

# Announce whether or not your server supports Forge. If you run a modded server, we
# suggest turning this on.
# 
# If your network runs one modpack consistently, consider using ping-passthrough = "mods"
# instead for a nicer display in the server list.
announce-forge = false

# If enabled (default is false) and the proxy is in online mode, Velocity will kick
# any existing player who is online if a duplicate connection attempt is made.
kick-existing-players = false

# Should Velocity pass server list ping requests to a backend server?
# Available options:
# - "disabled":    No pass-through will be done. The velocity.toml and server-icon.png
#                  will determine the initial server list ping response.
# - "mods":        Passes only the mod list from your backend server into the response.
#                  The first server in your try list (or forced host) with a mod list will be
#                  used. If no backend servers can be contacted, Velocity won't display any
#                  mod information.
# - "description": Uses the description and mod list from the backend server. The first
#                  server in the try (or forced host) list that responds is used for the
#                  description and mod list.
# - "all":         Uses the backend server's response as the proxy response. The Velocity
#                  configuration is used if no servers could be contacted.
ping-passthrough = "DISABLED"

# If not enabled (default is true) player IP addresses will be replaced by <ip address withheld> in logs
enable-player-address-logging = true

[servers]
# Configure your servers here. Each key represents the server's name, and the value
# represents the IP address of the server to connect to.
mchprs = "127.0.0.1:25565"

# In what order we should try servers when a player logs in or is kicked from a server.
try = [
    "mchprs"
]

[forced-hosts]
# Configure your forced hosts here.
"mc.frfrnocap.men" = [
    "mchprs"
]

[advanced]
# How large a Minecraft packet has to be before we compress it. Setting this to zero will
# compress all packets, and setting it to -1 will disable compression entirely.
compression-threshold = 256

# How much compression should be done (from 0-9). The default is -1, which uses the
# default level of 6.
compression-level = -1

# How fast (in milliseconds) are clients allowed to connect after the last connection? By
# default, this is three seconds. Disable this by setting this to 0.
login-ratelimit = 1500

# Specify a custom timeout for connection timeouts here. The default is five seconds.
connection-timeout = 10000

# Specify a read timeout for connections here. The default is 30 seconds.
read-timeout = 30000

# Enables compatibility with HAProxy's PROXY protocol. If you don't know what this is for, then
# don't enable it.
haproxy-protocol = false

# Enables TCP fast open support on the proxy. Requires the proxy to run on Linux.
tcp-fast-open = false

# Enables BungeeCord plugin messaging channel support on Velocity.
bungee-plugin-message-channel = true

# Shows ping requests to the proxy from clients.
show-ping-requests = false

# By default, Velocity will attempt to gracefully handle situations where the user unexpectedly
# loses connection to the server without an explicit disconnect message by attempting to fall the
# user back, except in the case of read timeouts. BungeeCord will disconnect the user instead. You
# can disable this setting to use the BungeeCord behavior.
failover-on-unexpected-server-disconnect = true

# Declares the proxy commands to 1.13+ clients.
announce-proxy-commands = true

# Enables the logging of commands
log-command-executions = false

# Enables logging of player connections when connecting to the proxy, switching servers
# and disconnecting from the proxy.
log-player-connections = true

# Allows players transferred from other hosts via the
# Transfer packet (Minecraft 1.20.5) to be received.
accepts-transfers = false

[query]
# Whether to enable responding to GameSpy 4 query responses or not.
enabled = false

# If query is enabled, on what port should the query protocol listen on?
port = 25565

# This is the map name that is reported to the query services.
map = "frfrnocap"

# Whether plugins should be shown in query response by default or not
show-plugins = false