Error Logs of Router system.logs

[#1]

I can see the below entry occurring continuously in system.logs of router

ERROR o.a.c.f.r.c.PathChildrenCache - PathChildrenCache.handleException() : 
java.lang.NullPointerException: null
2016-09-26 05:38:47,522  Router-ClientThread-0-3 ERROR Proxy-session - RouterProxySession$ClientContext.onTimeout() : Message Id: xxxx.abc.com_BVypKQhM_RouterProxy-14-7956_2 Session state: CLOSED MP channel [id: 0x95d0fa6b, 0.0.0.0/0.0.0.0:35560 :> xxxx.abc.com/***.**.**.**:****] timed out
2016-09-26 05:38:47,929  Apigee-Timer-3 WARN  CONNECTION-REAPER - ConnectionReaper$ReaperTask.safeRun() : Client-Connection-Reaper reaped inactive client connections [[id: 0x8cbda008, /1**.**.**.**:***** :> 0.0.0.0/0.0.0.0:****]]

In the meantime all request are getting timeout. The on premises device which we are currently using is 4.15.04.00.

Any thought's on this will be really helpful.