Got a question re. Hostapd and its bridge configuration. Look at these settings in a hostapd.conf.

wlan1 is the AP interface.

What does setting the bridge iface actually do?

A source iface will be added to the bridge br0. Then what becomes the purpose of wlan1?

Which iface will clients on the AP get network access? br0 or wlan1?

The Bridging idea is that 2 network interfaces get combined as a third bridging interface. This idea was around in the days of dialup modems which ran at very low speed, but unless you know the far end supports bridging, it doesn't.

It's also worth examining where the bottleneck is in your network traffic. On my system, the internet connection is the bottleneck. Back in the 1980s, 1200/300 baud modems were common. You could download at 1200bps, but you only uploaded at 300bps (because the other guy was presumably paying for the phone call ). So with 2 folks using these, comms were limited to 300bps. My first modem was 2400/2400 bps. With bridging, under those realities speed could be nearly doubled if you had two modems and two connections.

Laziest to check for bridging support, and forget it when you realise you haven't got it. Comment out the line on bridge interface. You don't need/want it.

Seems I need/want it.

I would like to bridge two wifi interfaces but I can't with WDS. 4addr seems unsupported on the infstructure.

What this boils down to is some sort of v.iface where traffic from both ifaces can be combined. A v.iface can be a bridge (or virtual bridge)?

This is what NAT does. I'm looking for a replacement to NAT.

For example when I setup a DHCP server would I use br0 or wlan1 as the exterior iface?

From the text in the example hostapd.conf:
Thought I've never tested it, it seems wlan1 would get stuffed into br0 and the traffic from wlan1 would appear in br0. I don't use this setting, but I stuff wlan0 into br0 in my setup. You'd serve DHCP on br0.

1 members found this post helpful.