Your service provider might've throttled your internet, could be a number of reasons. The ISP your connected to could have a large amount of other users connected to this and might be slow due to their usage too or, you've hit your monthly usage limit and they've capped your download limit by slowing down your speed. Some providers do this instead of charging you for going over your monthly usage limit, some charge too. You say it's also happening to other connected network items, so either of the above maybe true. Best ring your network service provider and ask them why it's slow.