Its most likely your Internet service proivder, I had a very bad spell once when my provider was going through "upgrades"
Try switch off all bandwidth using programs on your Home network (All computers in the house) like torrents and internet video streaming, etc. These can cause dc.
If your on wireless It could also be that your connection signal is bad or your neighbour is hacking you through your router and/or using up your bandwidth.
Finally look at this post
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Its failrly new and seemed to help me.