Running TeamViewer full version, 15.0.8397, I create a session code. The client uses the code at get.teamviewer.com, downloads TeamViewer QS and gets the green "ready to connect" message. I get the message "Service case is online". So far so good. But when I then try to prompt for remote control of the client machine I get 2 error message boxes. The first says "The remote TeamViewer is running an old version which is out of date. Therefore you cannot connect to this version anymore. Your connection partner can update TeamViewer by clicking on Help - Check for new version." Then next box says "Unable to connect. Reason unknown".
Very strange considering both the client with TeamViewer QS and the Full version which is trying to connect are runing the latest versions of Team Viewer.
I was interested in using team viewer commercially, but I can't even get off the launchpad.