Upon loading a custom modpack using this and a few other 1.8.9 mods, I receive the following fatal crash, which seems to indicate you're calling a client-side method on the dedicated server running this mod. (Very similar to this issue with another mod, if that helps any.) Not quite sure why it isn't reported elsewhere, or what may be causing this issue in this pack.

---- Minecraft Crash Report ----

WARNING: coremods are present:
ThaumcraftLoader (Thaumcraft-1.8.9-5.2.4.jar)
MalisisCorePlugin (malisiscore-1.8.9-2.1.6.jar)
IC2core (industrialcraft-2-2.3.247-ex18.jar)
LoadingPlugin (FastLeaveDecay-1.2.jar)
LoadingPlugin (HardcoreDarkness-MC1.8.8-1.8.jar)
LoadingPlugin (RandomThings-MC1.8.9-3.6.6.jar)
Contact their authors BEFORE contacting forge

// Sorry :(

Time: 5/19/16 6:09 AM
Description: Exception in server tick loop

net.minecraftforge.fml.common.LoaderException: java.lang.NoSuchMethodError: net.minecraft.item.Item.func_77640_w()Lnet/minecraft/creativetab/CreativeTabs;
at net.minecraftforge.fml.common.LoadController.transition(LoadController.java:162)
at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:744)
at net.minecraftforge.fml.server.FMLServerHandler.finishServerLoading(FMLServerHandler.java:97)
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStarted(FMLCommonHandler.java:325)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:205)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:441)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NoSuchMethodError: net.minecraft.item.Item.func_77640_w()Lnet/minecraft/creativetab/CreativeTabs;
at mrriegel.storagenetwork.helper.Util.init(Util.java:47)
at mrriegel.storagenetwork.proxy.CommonProxy.postInit(CommonProxy.java:32)
at mrriegel.storagenetwork.StorageNetwork.postInit(StorageNetwork.java:65)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:560)
at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
at com.google.common.eventbus.EventBus.post(EventBus.java:275)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:211)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:189)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
at com.google.common.eventbus.EventBus.post(EventBus.java:275)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:118)
at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:742)
... 5 more

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

-- System Details --
Details:
Minecraft Version: 1.8.9
Operating System: Linux (amd64) version 2.6.32-431.el6.x86_64
Java Version: 1.8.0_40, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 3397556152 bytes (3240 MB) / 3952607232 bytes (3769 MB) up to 3952607232 bytes (3769 MB)
JVM Flags: 3 total; -Xmx4096M -Xms4096M -XX:MaxPermSize=256m
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP 9.19 Powered by Forge 11.15.1.1875 43 mods loaded, 43 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
UCHIJ mcp{9.19} Minecraft Coder Pack
UCHIJ FML{8.0.99.99} Forge Mod Loader
UCHIJ Forge{11.15.1.1875} Minecraft Forge
UCHIJ archmagus{0.8.0} Archmagus
UCHIJ Baubles{1.1.3.0} Baubles
UCHIJ aura{592} Aura Cascade
UCHIJ BiomesOPlenty{3.0.0} Biomes O' Plenty
UCHIJ BloodMagic{1.8.9-2.0.0-20} Blood Magic: Alchemical Wizardry
UCHIJ BuildCraft|Core{7.2.6} BuildCraft
UCHIJ BuildCraft|Silicon{7.2.6} BC Silicon
UCHIJ BuildCraft|Transport{7.2.6} BC Transport
UCHIJ BuildCraft|Builders{7.2.6} BC Builders
UCHIJ BuildCraft|Energy{7.2.6} BC Energy
UCHIJ BuildCraft|Robotics{7.2.6} BC Robotics
UCHIJ BuildCraft|Factory{7.2.6} BC Factory
UCHIJ Chameleon{1.8.9-1.1.2} Chameleon
UCHIJ chisel{@Version@} Chisel
UCHIJ ComputerCraft{1.78} ComputerCraft
UCHIJ FastLeaveDecay{1.1} Fast Leave Decay
UCHIJ GraveStone{1.0.0} GraveStone
UCHIJ HardcoreDarkness{1.8} Hardcore Darkness
UCHIJ mantle{1.8.9-0.9.2.jenkins102} Mantle
UCHIJ tconstruct{1.8.9-2.2.1.jenkins1005} Tinkers' Construct
UCHIJ ImmersiveEngineering{0.8-26} Immersive Engineering
UCHIJ IC2{2.3.247-ex18} IndustrialCraft 2
UCHIJ InfernalMobs{1.6.6} Infernal Mobs
UCHIJ IronChest{6.0.125.770} Iron Chest
UCHIJ lucky{7.0.2} Lucky Block
UCHIJ malisiscore{1.8.9-2.1.6} MalisisCore
UCHIJ malisisdoors{1.8.9-3.1.4} MalisisDoors
UCHIJ testdummy{1.0} MmmMmmMmmMmm
UCHIJ progressiveautomation{1.6.44} Progressive Automation
UCHIJ ProjectE{1.8.9-PE1.1.4} ProjectE
UCHIJ Psi{beta-23} Psi
UCHIJ quantumflux{2.0.1} QuantumFlux
UCHIJ randomthings{3.6.6} Random Things
UCHIJ SoulShardsTOW{1.8.9-2.2.8-16} Soul Shards - The Old Ways
UCHIJ StorageDrawers{1.8.9-2.6.4} Storage Drawers
UCHIE storagenetwork{1.10.0} Storage Network
UCHIJ Thaumcraft{5.2.4} Thaumcraft
UCHIJ Waila{1.6.0} Waila
UCHIJ YALSM{2.1.5} Yet Another Leather Smelting Mod
UCHIJ denseores{1.0} denseores
Loaded coremods (and transformers):
ThaumcraftLoader (Thaumcraft-1.8.9-5.2.4.jar)

MalisisCorePlugin (malisiscore-1.8.9-2.1.6.jar)
net.malisis.core.util.chunkcollision.ChunkCollisionTransformer
net.malisis.core.util.chunkblock.ChunkBlockTransformer
net.malisis.core.renderer.transformer.MalisisRendererTransformer
net.malisis.core.renderer.icon.asm.TextureMapTransformer
IC2core (industrialcraft-2-2.3.247-ex18.jar)

LoadingPlugin (FastLeaveDecay-1.2.jar)
lumien.fastleavedecay.asm.ClassTransformer
LoadingPlugin (HardcoreDarkness-MC1.8.8-1.8.jar)
lumien.hardcoredarkness.asm.ClassTransformer
LoadingPlugin (RandomThings-MC1.8.9-3.6.6.jar)
lumien.randomthings.asm.ClassTransformer
Pulsar/tconstruct loaded Pulses:
- TinkerCommons (Enabled/Forced)
- TinkerWorld (Enabled/Not Forced)
- TinkerTools (Enabled/Not Forced)
- TinkerSmeltery (Enabled/Not Forced)
- TinkerGadgets (Enabled/Not Forced)
- TinkerOredict (Enabled/Forced)
- TinkerIntegration (Enabled/Forced)
- TinkerFluids (Enabled/Forced)
- TinkerMaterials (Enabled/Forced)

Profiler Position: N/A (disabled)
Is Modded: Definitely; Server brand changed to 'fml,forge'
Type: Dedicated Server (map_server.txt)

In case this gets noticed, the crash doesn't occur if I downgrade to Storage Network v1.9.2 so it's most likely caused by a commit that occurred between that version and the one I used originally (v1.10.0).

Thanks Riegel!