On Sat, 4 Mar 2017 05:47:06 -0800 (PST), Lobster wrote:

Yep. Setup here comprises a Virgin Superhub 2, in modem+router mode, which spits out WiFi on SSID 1, connects to a conventional CAT5 LAN, and also to an adjacent 'Powerline' device which pumps my network signal into the mains. At the far end of my house is the TP-Link PowerLine device, which just provides WiFi for that area, on SSID 2

I've never quite understood the whole speed-halving malarkey;

On a given channel only one thing can transmit at a time. With a
repeater (aka extender) retransmitting on the same channel as the
AP
each packet is transmitted twice, once from the AP then again from
the repeater. Thus halving the number of time slots available.

OK. Does that apply only to a wifi extender; ie one which sucks in a
weak signal and boosts it over a wider range (if I'm getting that
right?)

Yes.

So (assuming low traffic, which is fair enough) are you saying there's
no benefit to my current arrangement at all, and I'd be better off
putting both on the same SSID, same channel then?

Same SSID I pretty sure isn't a problem at all. If the coverage areas
of the two AP's overlap having them on different channels will stop
them stomping on each other or having to wait. It's also a bit
dependent on whether the two APs can hear each other if on the same
channel. If they can they won't transmit at the same time. If they
can't they might which will make things messy in the overlap area
when traffic levels are high.

If the total traffic from each AP is greater than the maximum
bandwidth available on one WiFi link. ie if the WiFi can support 40
Mbps, you could have one AP shifting data at 38 Mbps the other
shifting data at 2 Mbps without serious problems. But is that 2 Mbps
became 10 Mbps it would start to get messy.

--
Cheers
Dave.