I am having a very strange problem with remote control software. I have a MacbookPro with OSX El Capitan 10.11.6. Initially I connected to this box over wifi using the built-in VNC server, and TightVNC viewer (on Windows 7). All worked well until about a month ago. The initial VNC connection started to take longer and longer to establish, and performance went through the floor... it was taking 30 seconds to repaint. So, I decided to give VineServer a try. Initially it worked great, connecting with TightVNC as before, nice rapid connections and good performance. After a couple days, it too began to slow down, with freezes during logons and the same performance slowdown I had seenn with OSX VNC server (which was turned off). I decided to try one more VNC option... I turned off VineServer and installed RealVNC server and client. The same thing happened... freezes on logon and performance through the floor.
Having had all these problems with every VNC server/client pair I could think of, I turned to NoMachine, which promised to avoid the whole problem by using a different protocol entirely. I installed it, seemed to work fine, but then the same thing happened... freezes during logon, terrible repaint and mouse pointer capture.
What could cause the same problems across four servers and two protocols? It isn't the wifi itself, I have excellent connectivity across that.