Hello Larry,
Thank you for your message.
1) Not able to stay connected, constantly having to stop and start host (using [censored] !?!?).
If you mean the "Access denied" bug, you didn't need to start/stop Host for that. You could jus log off / log back on (in Remote Utilities).
Anyway, yesterday we released version 6.1 that fixed that bug altogether. You can download it here
https://www.remoteutilities.com/download/2) Still unable to use the arrow keys.
Try the new version.
3) Stupid problem with security mode not supported when trying to connect to remote host
This is the bug from p.1.
4) and now, can't install 5.6 (which worked!) because of an error during install about "Unable to Read TROMServerOptions" which I found on the forums but never saw a fix for it.
Just install the latest 6.1 and see if it works for you. Make sure that you upgrade both parts - Viewer and Host.
If you have any issues, please let us know.