Just wanted to add my two cents. Starting version 188.8.131.52 we improved the installation process for the Host (you may have noticed that - there's now .exe Host available and also the installation window changed a bit). The purpose of this improvement was to make sure that the Host service restarts guaranteed after the simple update instead of delegating this task to Windows msi which wasn't always reliable in this respect. So if you are updating from 184.108.40.206 to 220.127.116.11 you are already using the new process (unfortunately, it doesn't work retrospectively, i.e. updating from 18.104.22.168 and earlier to 22.214.171.124 won't trigger this mechanism).
Yet, even with that precaution made there may be situations when Host service may not start due to some reasons, such as a/v software activity or security policy (this is true about Windows Server especially). We cannot control these factors though, unfortunately, and it is up to the user/customer to take them into account.
This caution sign means that the Host's version is outdated (i.e. with respect to the Viewer version, not in absolute figures). The information about Host version on the Viewer side is updated the next time you log in on the remote Host from that Viewer. In earlier program versions when you updated the Host and haven't logged in on it yet there may still be a caution sign even if the Host status is Online.
In the future we'll make the program update Hosts' "update statuses" immediately during the online status without the user having to log in on the Hosts. Meanwhile, in the latest RU update (126.96.36.199) we partially resolved this issue so when you run the Simple update process the caution sign disappears right away without waiting for update status confirmation by logging in on the Host.