Unexpected high downloads on broadband

[#1]

We are experiencing occasional high download levels of between 4 and 14 GB. These are usually overnight but, on a couple of occasions, have been during daytime. Initially we thought it was a neighbour logging into our system on an unsecured wireless portal but we've changed that equipment and tightened up access permissions on the router but it's still happening.
We have an imac, an ipad and 2 iphones plus a cable-connected Panasonic smart tv. The imac has antivirus software on it.
Plusnet can tell us what time of day it's happening but nothing more.
Does anyone out their recognise this issue and have any suggestion about what could be causing it?

[#2]

Hi 'Derekpsmith', and welcome to the forum !  


Try fully switching off your iPhones and iPad overnight.
I have observed that on occasions that iPhones and iPads left overnight seem to upload an their entire contents to somewhere on the internet.  This got so bad for us, that in the end I set up a separate Wireless Access Point on our home network just for the Apple mobile devices, and that access point is set so that all internet access is blocked overnight, and the problem was immediately solved.  I did try time limiting the IP addresses that were being contacted, but the Apple devices kept finding new alternatives - and I gave up trying at around 40 blocked destinations - all of them being anonymous IP addresses all around the world !
The other thing, is have you had a modem/router on Plusnet that you have sold or given away without clearing the settings ?
It has happened before that Plusnet customer's old routers have ended up in the hands of another Plusnet customer who hasn't changed the internet settings, the result is the new owners internet usage gets recorded on the previous owners account.  This can be fixed by changing your Plusnet "Member Centre" password, updating the new password in your router, and restarting your connection.  Eventually the other owners router will need to reconnect but will subsequently fail, or you could ask Plusnet to restart all your PPP sessions which would force the other user offline.

[#3]

Thanks for your really helpful response Purleigh. We've started doing what you've suggested and turned things off at night but we haven't always remembered! After your response we will be more diligent and do it every night and see if that eliminates the problem.
I like Apple's gear but they do seem to operate by a different set of standards!

[#4]

The specific feature is iCloud backup of your devices. To disable this you need to use iTunes, connect iDevice to computer and set the preference to backup onto computer rather than the current iCloud setting. Remember, you have to do this for each of your iDevices.
Another thing that could use your data is iOS software updates. These thankfully only happen not so often and only when the iDevice is connected to a power source.

[#5]

Thanks RPM, I was pretty sure we weren't set up to use iCloud but it was a useful reminder and I've reconfirmed those settings on iTunes.

[#6]

There isn't actually much upload usage showing, it's mainly downloads so it's unlikely to be iCloud backups.
It might be system updates, streaming videos or similar, but it's very hard to give details really. We can supply break it down by hour (upload/download) for a day or 2 if you like?

[#7]

Thanks Chris, we've had a couple of timed reports which confirmed for us that it wasn't anything we were doing because we were asleep. As you say we think that there might have been a system update or similar but there doesn't seem t be a way of finding out more details from our Vodafone, our equipment logs or Plusnet. We'll just remain vigilant.