For other's that may read this or have seen the entry in their SQL Monitor, a microsoft##wid SQL instance is a Windows Internal Database - a variant of SQL Server Express. Please find more information on WID here. These are nothing to do with SQL Monitor other than we attempt to monitor them (we auto discover all SQL Instances on the target machines) so something you have installed will have added this to your system. Based on the information in the article above, you will not be able to log into it remotely and if it is local to the base monitor server you will need to use windows authentication with named pipes it seems.
I've just checked the code and it looks like in the latest version (8.0.5 as of this writing) that when we are auto-discovering the instances, we check if it is suffixed with ##wid and do not add the instance if this is the case.
In earlier versions where it wasn't the case that we didn't discover these instances, all instances are automatically discovered and we cannot remove it from being monitored, but you can suspend it from monitoring (by click on the cog wheel at the right and choosing suspend monitoring) and this will prevent alerts from being raised and will remove it from the Overview and Alerts pages.
Alternatively, updating to the latest version 8.0.5 and then removing the entity (making sure not to delete the existing data as this will affect the data for the server and other SQL instances) and then re-adding the entity should discover everything but the Windows Internal Database.
I hope that helps clarify what this is and expected behavior!
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