mac to mac black screen or stuck at login screen

I have seen various posts reporting a black screen or stuck at the login screen when using TeamViewer to connect from one mac to another remote mac. I use TeamViewer to frequently connect to remote windows PC's over challenging internet connections (the remote machines are on ships and have unreliable internet so a team viewer connection isnt always workable. (Those machines are completely unatended so all **bleep** breaks loose when I can't connect) My office computer however is an iMac and when I'm out and about I like (sorry NEED) to be able to connect to my iMac. I'm using TeamViewer 13 and pay for it. Now in this version (and in previous versions) I have often been unable to connect and get as far as a black screen (previously I have put this down to Rapport security software (used by internet banking to prevent screen capture and a real nuisance - **bleep** I forgot to close the web browser after making that payment!!!)) OR get as far as a login prompt BUT mouse and keyboard wont let me login. The screen appears frozen. Then maybe I'll try file transfer BUT it says blocked by remote or something like that. As a last resort I send someone to the office in order to restart computer or TeamViewer. Remote control should mean Remote control is ALWAYS available and should not mean sending your wife to the office in the middle of the night just because TeamViewer isnt working. What are your suggestions for ensuring TeamViewer will always allow remote access. Also why cant I remote upgrade those unattended windows PC's theyre ALL still using an old TeamViewer version. I just get a message saying remote update failed!!!