Help with cabal

I'm setting up my GHC builds on a new machine, and this time I'm using WSL (windows subsystem for Linux). Small problem. I've installed cabal-3.0, and say "cabal update". But I get Unexpected response 502for http://hackage.haskell.org/timestamp.json And indeed, that's what a web browser says for that same URL. What do to? Oddly, on another also-new Windows machine, I do exactly the same thing, and with 'cabal update -v' I can see that it gets the same error, but then moves on to try hackages.fpcomplete.com, which works. Why does the behaviour differ? And, at least for now, how can I get the first machine to look at hackage.fpcomplete.com? Thanks Simon