This has happened twice now - the first time I changed my password and hid my router name from public searches which seamed to do the trick, but it's started doing it again tonight. Even if no phone or computer is using the internet and we're not streaming anything, when the WiFi is on the internet light flashes like the internet is in use, like something is being streamed / downloaded. This doesn't happen is the WiFi is turned off on the router.
Should be be worried by this? Is it just a connection test or check? Is there anything I can do (like MAC address filtering) just in case?
Fixed! Go to the fix.