Question: Every now and then I get the "zlibinstream:exceeded bytesIn" error when trying to connect to my server through my vnc. Why do I get this error and how can I solve it when I get it - without restarting my server ?

Answer: 
In my case the solutions is just to change quality to `Low`. Seems to work fine.
Just for the googlers out there that find this question: Changing the "prefered encoding" to something other than "ZRLE" (I used "hextile")is what solved the issue for me.