Workaround: Synology DSAssistant
For some reason DSAssistant.exe does not work well with Internet Security software. So I found that if you don't need to look at the Resource Monitor, or add a printer, or do something with photoupload, then you can just connect directly to the Synology Diskstation through a browser.
Where the ip address is the ip assigned to the diskstation. This way, you bypass the DSAssistant and keep your Internet Security package working.