I got a pair of these and a paid of 500's.

I didn't realise pairing was about encryption so thanks for that! They worked out of the box so just left them.

Since I have four, how would I pair them? Naturally one feeds the broadband and the other three suck it out...

Performance has been great though, the broadband line is 76MB and they pass out 66-69MB which is much less loss than I expected.