add retry for socket scanning with delay

[fliepeltje]

possibly closes #3761 and possibly closes #3358

[KTanAug21]

Also! @fliepeltje, something to ponder about: would you consider reducing the sleep time to 1 second for each retry?

1. Pro: This will reduce wait time in case the services becomes reachable earlier than 3 seconds
2. Con: You'll have to increase the number of retries though! Since the intended logic is that most services are reachable by 3 seconds, when reducing the sleep time to 1 second, the retries have to be increased to reach that 3 second mark. So that's a drawback, since that would increase requests made to the app right.

Also this is a very experimental question, with the aim of taking into consideration the wait time of users. But if 3 seconds is not that long, and is not any different from waiting 1 second, then I guess this comment don't need to considered even.