I update my server 1.8.3 and disconnect players this messages:

Client: NetworkDispatcher exception
io.netty.handler.timeout.ReadTimeoutException

Server: player lost connection: TextComponent{text='Disconnected', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}

Plugins (52): GroupManager, PlugMan, CustomRecipe, AntiBotUltra, ChatColor, CoreProtect, WorldEdit, FrameProtect, Essentials, JP2048, ClearLag, ChatControl, AutoMessage, Chairs, ProtocolLib, NoCheatPlus, LibsDisguises, NoNBT, RedstoneClockDetector, EssentialsChat, BlocksHub, Vault, ProtocolSupport, BlocksHub-CoreProtect, WorldGuard, SkinsRestorer, BlocksHub-WorldGuard, monkeysLockette, EssentialsGeoIP, EssentialsAntiBuild, EssentialsSpawn, PlayerHeads, CombatLog, PlotMe, Jobs, SimpleRegionMarket, Multiverse-Core, WhatIsIt, TreasureChest, AsyncWorldEdit, VanishNoPacket, CraftBook, ChestShop, AuthMe, floAuction, MobArena, LimitedCreative, MineMarket, TitleManager, MyPet, iZone, Paintball