That doesn't sound like an issue with the Hub 3.0, there isn't anything on the hub that would prompt a pop-up to appear if there's a connection problem. The hub should remain connected as long as it's powered up, so it wouldn't try to connect when you boot up the PC.
I would recommend running an anti-virus / spyware scan to ensure that the PC hasn't picked up anything that it shouldn't have done.
Thanks for that, are you using Windows 10 as well by the way. It does sound like it may be a windows thing looking for an internet connection and when it doesn't see one while the hub is initialising it tries to be helpful by opening a link to the hub default gateway, maybe a little too helpful. Similar to Windows 7 I guess where the system tray icon would show no internet connection for a while despite being able to browse.
It still takes quite sometime on booting to fully connect to the Hub3 but it gets there after a minute or two.
Ditto, takes several minutes every morning now. But even worse at the moment is the flaky service, it's been going up and down all day, TV channels lost, and this has been happening for a few weeks.
When the network goes I get that tool_troubleshoot screen, but as it looks like those spam sites that try to tell you you are infected and lock your browser screen, I've immediately closed it. Doesn't say who it's from, if it is Virgin as seems to be the case then it's very bad.