I know it is bug from Eclipse, but it blocks user to starting use a STS.
In my situation I connected to internet through corporate proxy.
Proxy is specified in system settings of MacOS, so Eclipse gets this settings on first launch (in a normal situation Eclipse never was able connect to internet using this setting, so each clean installation I'm specifying it manually).
On first start STS is loading empty perspective and after that not responding.
I know it trying initialize dashboard, but it can't connect to servers and blocks everything, including preferences to change network connections settings.
In workspace log of course exists java.net.SocketTimeoutException: Read timed out