Any question answered...

Can you explain this with a bit more detail (but so much that I don't understand!)?

The Internet isn't just one big thing. It's lots of smaller networks that talk to each other (by peering with each other) with rules about how to route traffic between them all.

Your university (via JANET) may be peering more closely with the site hosting LFGSS (very likely given the owner's employer which specialises in DDoS protection).

So the traffic between your computer and the LFGSS server(s) may not go anywhere near any of the links/peers that have been saturated by the DDoS. Whilst most other sites you want to visit involve being routed via somewhere that's saturated by the DDoS, and you just get timeouts or DNS lookup failures.

A shit analogy would be the UK road network. If the nearby motorway is hosed then traffic to most of the country is shagged, but you could still get to the house next door easily (=> the local network is ok), a house in the next road (a computer in the office next door), a house in the same town (another computer on campus), maybe the next town (a computer at a company that is served by the same network provider or someone that peers directly with your network provider), but anything further than that (which requires the main roads) is impossible.

(Plenty of people will be along to correct me on this and/or give better explanations. Feel free everyone.)