This just started in the last few months. Not sure if it was before the 18.104.22.168 update or not.
The service is running, but the system tray icon is grey when it happens. I can remote into another system and then restart the host on my machine just fine. So that other machine doesn't have this issue. Once I restart the Host, I can connect just like I always have, but after a period of time, it will disconnect. I have timed it, but I would say it's 15-30 minutes. Then when I remote into another machine and into this one (using UltraVNC), I can restart the Host and connect again. I have have Sophos on this machine and not the other, so maybe something there?
The issue might be caused by some antivirus software activity, for example, if Sophos is mistakenly blocking Host service. Could you please try adding the following Host installation folder to the Sophos exception list and see if it helps to resolve the issue: C:\Program Files (x86)\Remote Utilities - Host\? Here's how you can add an exception for Sophos. In addition, if the above suggestion helps to resolve the issue, please feel free to to submit a false positive report on this page.
Of course, please feel free to let us know if adding the exceptions helps to resolve the issue. In addition, you can also submit a false positive report to Sophos in order to resolve the issue on their side as well.
Please let us know if the issue persists or if you have more questions.