https://community.teamviewer.com/English/discussion/72031/~/English/kb/security-handbook
Unexpected CCommand 21 when connecting to TeamViewer 14 - TeamViewer Community
A PC in our network is having an issue where after a while it will not allow connections, and throw an error below.. Error during connection The PC appears to...
unexpectedconnectingteamviewercommunity
https://community.teamviewer.com/English/discussion/72025/unexpected-ccommand-21-when-connecting-to-a-client/p1
Unexpected CCommand 21 when connecting to a client. - TeamViewer Community
a clientunexpectedconnectingteamviewercommunity