Active public servers include:

flent-freemont.bufferbloat.net
( this is colocated with flent-bbr-west which has bbr on by default - an
interesting test might be testing both these servers at the same time
via the rtt_fair* tests from your location)

flent-dallas.bufferbloat.net
flent-london.bufferbloat.net
flent-tokyo.bufferbloat.net
flent-newark.bufferbloat.net