I've been having problems with ESO including constant DC's about every 30minutes. I've researched this, and have been told to contact my ISP. Disconnects either happen at the end of loading screens or are random. I have also noticed very long loading times compared to other users. Apparently Virgin are aware of the issue.
I have tried a static IP, port forwarding, router resets, new PC hardware and from researching online, getting a new router with the latest firmware (or version of firmware that works with ESO) is the solution.