This will happen when you getting traffic in your network. Due to your CAS server and MUX has been not able to communication lagging network traffic. You must reduce the traffic instantly check your ping latency to particular IP’s and check your MUX ECMG connection
If it getting without error then automatically error will gone.
As well you must check with your ECMG tag which your made recently in you CAS. if they been any mistakenly then you might get this error often. so please verify that too.