I've noticed if Serviio is running, and is able to stream media to my TV, once i put the TV on standby, and switch it on, i must refresh the client list before the state is green (online) before i can stream media again. This may be caused by putting the TV on standby, and then rebooting my system, haven't tested this yet.
Is Serviio detecting the TV correctly? ie not unknown device.
What this sounds like is that when the TV is in standby it is turning off it's network connection. When the TV is taken out of standby, it takes a few seconds for the network connection to be re-established and then for Serviio to find it. I am not sure what the scan rate of serviio is to find new devices, but I would guess that is what is happening.
Have you placed the TV in standby and then turned it on and waited a short time and see if it is recognized by serviio automatically?
How do you have your IP addresses setup are they dynamic or static. dynamic means that the router sets them each time you turn on the device. Static means that they have the same IP address each time. If it is dynamic it could be taking a short period of time for the router to recognize the tv is on and assign it an IP Address only after that is complete can Serviio recognize it.
It is some time before i have to refresh the list myself, so either Serviio is just avoiding the states, and checking for new devices instead, or there is a long delay before it does re-search states. My IP is static, and my router also assigns static internal addresses to all of my devices.
Can you enable detailed logging (see signature) and put TV in standby and then turn it on and try and watch something. Then post the Detailed log here.