STA + AP mode + connecting to DFS Channels on uplink'ed AP

I managed to find an interesting issue when playing with my new travel router (AR750S from gl.inet). It actually looks like a couple issues that aren't quite covered elsewhere (man, I tried to search).

Anyhow, consider the following - my 750S using STA mode to connect to our wifi infrastructure as a client. We run multiple channels and both 2.4 and 5G with band steering. All SSIDs are the same name regardless of 2.4 or 5.

Locally, it's just your plain old 2.4 and 5G APs with separate SSIDs. Since one of the radios is doing double duty, it has to follow the channel of whatever it is connecting to for the uplink.

Today I found out that they're starting to roll out DFS channels in the office by accident - my 5G radio kept dying and coming back repeatedly. Looking in the logs:

Wed Oct  3 15:49:04 2018 daemon.notice hostapd: Channel 132 (primary) not allowed for AP mode
Wed Oct  3 15:49:04 2018 daemon.warn hostapd: wlan0: IEEE 802.11 Configured channel (132) not found from the channel list of current mode (2) IEEE 802.11a
Wed Oct  3 15:49:04 2018 daemon.warn hostapd: wlan0: IEEE 802.11 Hardware does not support configured channel

(cut for simplicity, hostapd promptly barfs and tries to restart, repeat)

It looks like STA mode is connecting to our SSID (I tried pegging this to a 2.4G channel), and then band steering is telling it "nah, cmon, 5G is where it's at, connect to this channel"...which happens to be 132/DFS. At which point OpenWRT informs me that while it's cool and all to connect STA via DFS channels, but the 5G AP doesn't support that same channel.

I haven't seen any radar detection logread messages, but I'd imagine it'd throw a fit as it'd see an existing wifi channel and refuse to spin up an AP on the exact same channel.

With that, some questions:

  1. How can I hard-peg STA to just that one AP and not let it band/channel hop? Or, I mean, is there some reason it can't do DFS in this situation (I may have answered myself with the last sentence re: radar).

  2. I've tried basic enabling of DFS channels (all regions marked as US) and get the following off of iw phy phy0 info:

			* 5180 MHz [36] (23.0 dBm)
			* 5200 MHz [40] (23.0 dBm)
			* 5220 MHz [44] (23.0 dBm)
			* 5240 MHz [48] (23.0 dBm)
			* 5260 MHz [52] (23.0 dBm) (radar detection)
			* 5280 MHz [56] (23.0 dBm) (radar detection)
			* 5300 MHz [60] (23.0 dBm) (radar detection)
			* 5320 MHz [64] (23.0 dBm) (radar detection)
			* 5500 MHz [100] (23.0 dBm) (radar detection)
			* 5520 MHz [104] (23.0 dBm) (radar detection)
			* 5540 MHz [108] (23.0 dBm) (radar detection)
			* 5560 MHz [112] (23.0 dBm) (radar detection)
			* 5580 MHz [116] (23.0 dBm) (radar detection)
			* 5600 MHz [120] (23.0 dBm) (radar detection)
			* 5620 MHz [124] (23.0 dBm) (radar detection)
			* 5640 MHz [128] (23.0 dBm) (radar detection)
			* 5660 MHz [132] (23.0 dBm) (radar detection)
			* 5680 MHz [136] (23.0 dBm) (radar detection)
			* 5700 MHz [140] (23.0 dBm) (radar detection)
			* 5720 MHz [144] (23.0 dBm) (radar detection)
			* 5745 MHz [149] (30.0 dBm)
			* 5765 MHz [153] (30.0 dBm)
			* 5785 MHz [157] (30.0 dBm)
			* 5805 MHz [161] (30.0 dBm)
			* 5825 MHz [165] (30.0 dBm)
			* 5845 MHz [169] (disabled)

I've seen a few other threads with my same chipset (ath10k) but their solution of setting US didn't seem to help. Maybe an issue with the modified gl.inet firmware? It'd be nice to at least have the DFS option for testing (I tried in AP only mode, no STA, with no luck).

Edit: I shut off the 5G radio, enabled STA mode, then re-enabled the 5G radio on 36. I'll report back ff it hops..

You can add an optional BSSID setting in your wireless config.
It will then only connect to the AP if:

  1. SSID matches
  2. BSSID matches
  3. Password matches

You’ll need to hunt down the BSSID of the interface you’re after.

Side note: what do you think of the AR750S. I was looking at one to play with to replace a previous “pocket sized router”, although this one looks a little bigger.

I don't think that any version of ath10k yet supports AP mode on DFS channels.

Both ath9k and ath10k support AP mode on DFS channels just fine, probably for all supported hardware, at least for ETSI, but I'm very confident that they support FCC and MKK probably as well.

Thanks! That's a good idea (a little manual work but worth it). I doubt I'll run into many DFS setups in the field with consumer gear but it's good to be prepared.

The 750S has been pretty nice so far - I've held off dumping the latest nightly on it because the gl.inet gui is so easy bake oven (and it solves my wireguard up/down issue). I might "borrow" some of their mechanisms and toss the stock OpenWRT on it once it's supported on a stable (vs snapshot) build. The antennas at least make me feel like I'm getting better range :slight_smile: and the three gigabit NICs are nice. Fair warning, you almost certainly need a 2A power supply for this, so watch out if you're trying to charge your phone/tablet on the same charger (speaking from experience).

@slh I noticed that the channels were listed as available but intentionally grayed out in the gl.inet settings. I'm wondering if it might be something in their firmware that's excluding it from the list.