Team viewer 13 unattended needs activity at client end to work

I have set up Team Viewer unattended access on my PC  at home allow me to connect as I am away from home regularly visiting the same place. I tested this from my destination before I left and it worked fine. However, when I got to the other end and tried to connect it said "Team Viewer not running". As it happens, someone was able to go into the house and all they did was switch on the monitor on the remote PC and suddenly Team Viewer connected and then ran OK for the rest of the day. This morning I've come to connect again and once again getting "Team viewer not running" message. Could it be remote PC going into some sort of sleep mode and just switching on the monitor wakes it up?

TIA

Nigel