TeamViewer is backwards-compatible, which means that newer versions are able to connect to any previous versions. While connected, you can even hit the Remote Update button in your toolbar to upgrade the endpoint remotely!
Click 'Remote Update' to bring the endpoint to the latest version!The only issue would be if an older version were to try to connect to a newer version; due to protocol negotiations this would not be possible.
I hope this helps!
Josh P. Senior Moderator
If my reply answered your question, help out other users and click the Accept as a Solution button below.