Since I switched to Wayland, I could not find an alternative for barrier that I used under X. After a lot of search I bumped into a project called rkvm. You can check it out. It is a bit more difficult to setup than barrier but it works pretty well for me.
The only bad thing is that both computers must run linux.
Is it possible to upgrade a Debian 8 (Jessie) to 9, 10, 11 and eventually 12? It is reccomended to upgrade one release at a time. But! 9's repositories are archived. How can I upgrade form 8 to 9?