So it appears the guest network is only available from the MR600, cos I moved the RE200 extender onto the same extension lead, and it was no better (which supports a theory my mate warned me about...

I have a couple of KP115 smart plugs connected up to Kasa to use with the equiwatt energy saving site. These plugs aren't behind the fridge, or buried in a cupboard, they're on an extension lead by...