I have the same problem, and have no idea why it is happening. As I said in my post requesting a Troubleshooting community category, the dLink Lite App I use for my dLink cameras has been working fine, so I know the Internet is fine at my weekend condo where I am using ST and the dLink cameras.
The power plug (hub end) for the hub seems to be hanging up on the hubs housing not letting it fully seat.
While checking it again, I pushed the plug in and gave it a little wiggle and could feel it move a little farther. Unplugged it, tried it again and the housing definitely will keep the plug from going in all the way. Give it a little wiggle and it will seat. Hadn’t had the problem since.
Not sure if it’s your problem but may be worth a shot.