Meraki MR18: 600Mbps possible?

Installing and Using OpenWrt
1

I finally got round to flashing my MR18 (the last time I tried was years ago when you had to get lucky with timing a split-second critical key press or something during boot). It was pretty easy in the end and I'm running OpenWrt 18.06.1 r7258-5eb055306f / LuCI openwrt-18.06 branch (git-18.228.31946-f64b152).

I'm planning on placing this AP on the diagonally opposite corner of the house, to provide a stronger Wi-Fi signal for streaming when far from the router.

At the moment, I just set up each radio to have the widest bandwidth to use channel bonding and ended up with:

radio0 (generic): 2.4GHz, ch1, max=20dBm (100mW), 40MHz, 144Mbps
radio1 (Atheros AR9580): 5GHz, ch52, 40MHz, max=20dBm (100mW), 300Mbps
radio2 (Atheros AR9580): 5GHz, ch60, 40MHz, max=8dBm (6mW), 150Mbps

I chose the channels to complement my router's radios on 2.4 and 5GHz. My router runs one radio on 2.4GHz channel 11, 40MHz. The other router radio is at the bottom of the 5GHz channels, so I put the MR18 5GHz above that:

Screenshot_20180830-224944

I think the channels and speeds are ok, but I was wondering if the two AR9580 radios can be configured so that they run in MIMO mode. Can they be set up on the same 5GHz channel and the hardware magically combines/bonds the two radios into one fat link? I would guess that the two matching Atheros radios can somehow be teamed together for better performance, but I can't find any examples of how this would be configured.

It's ok having the two 5GHz radios, but as they're in the same physical location, it seems that having them running seemingly independently is a bit pointless and means I'm missing out on the "2x2" and "MIMO" modes that this product's marketing boasts. Part of that claims a 600Mbps combined speed. Is that just all the separate radio link speeds summed together mathematically (and not in any network implementation)?

Also, does anyone have any ideas why my radio2 has a 8dBm (6mW) max transmit power when radio1 is 20dBm (100mW)?

2

have you check with stock firmware one of the radios is not management only? according to image one of the AR9582 chips isn't wired to any FEM so it might've been limited to 8dBm...

3

In the stock firmware, one of the radios monitors all Wi-Fi signals in the area, some of that presumably allows dynamic controls of the actual serving radios, for Tx power, channel, width, etc. for optimum running. Seems odd that the monitoring would be one of the AR9582 radios, but yeah I guess that would explain the 6mW Tx limit (as it wouldn't really need much for monitoring).

Aha, yes, radio2 is definitely the gimped one:

root@ap1:~# iw phy
Wiphy phy2
        max # scan SSIDs: 4
        max scan IEs length: 2257 bytes
        max # sched scan SSIDs: 0
        max # match sets: 0
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Retry short limit: 7
        Retry long limit: 4
        Coverage class: 0 (up to 0m)
        Device supports AP-side u-APSD.
        Device supports T-DLS.
        Available Antennas: TX 0x1 RX 0x1
        Configured Antennas: TX 0x1 RX 0x1
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * AP/VLAN
                 * monitor
                 * mesh point
                 * P2P-client
                 * P2P-GO
                 * outside context of a BSS
        Band 1:
                Capabilities: 0x11ef
                        RX LDPC
                        HT20/HT40
                        SM Power Save disabled
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 8 usec (0x06)
                HT TX/RX MCS rate indexes supported: 0-7
                Frequencies:
                        * 2412 MHz [1] (11.0 dBm)
                        * 2417 MHz [2] (11.0 dBm)
                        * 2422 MHz [3] (11.0 dBm)
                        * 2427 MHz [4] (11.0 dBm)
                        * 2432 MHz [5] (11.0 dBm)
                        * 2437 MHz [6] (11.0 dBm)
                        * 2442 MHz [7] (11.0 dBm)
                        * 2447 MHz [8] (11.0 dBm)
                        * 2452 MHz [9] (11.0 dBm)
                        * 2457 MHz [10] (11.0 dBm)
                        * 2462 MHz [11] (11.0 dBm)
                        * 2467 MHz [12] (11.0 dBm)
                        * 2472 MHz [13] (11.0 dBm)
                        * 2484 MHz [14] (disabled)
        Band 2:
                Capabilities: 0x11ef
                        RX LDPC
                        HT20/HT40
                        SM Power Save disabled
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 8 usec (0x06)
                HT TX/RX MCS rate indexes supported: 0-7
                Frequencies:
                        * 5180 MHz [36] (8.0 dBm)
                        * 5200 MHz [40] (8.0 dBm)
                        * 5220 MHz [44] (8.0 dBm)
                        * 5240 MHz [48] (8.0 dBm)
                        * 5260 MHz [52] (8.0 dBm) (radar detection)
                        * 5280 MHz [56] (8.0 dBm) (radar detection)
                        * 5300 MHz [60] (8.0 dBm) (radar detection)
                        * 5320 MHz [64] (8.0 dBm) (radar detection)
                        * 5500 MHz [100] (8.0 dBm) (radar detection)
                        * 5520 MHz [104] (8.0 dBm) (radar detection)
                        * 5540 MHz [108] (8.0 dBm) (radar detection)
                        * 5560 MHz [112] (8.0 dBm) (radar detection)
                        * 5580 MHz [116] (8.0 dBm) (radar detection)
                        * 5600 MHz [120] (8.0 dBm) (radar detection)
                        * 5620 MHz [124] (8.0 dBm) (radar detection)
                        * 5640 MHz [128] (8.0 dBm) (radar detection)
                        * 5660 MHz [132] (8.0 dBm) (radar detection)
                        * 5680 MHz [136] (8.0 dBm) (radar detection)
                        * 5700 MHz [140] (8.0 dBm) (radar detection)
                        * 5745 MHz [149] (disabled)
                        * 5765 MHz [153] (disabled)
                        * 5785 MHz [157] (disabled)
                        * 5805 MHz [161] (disabled)
                        * 5825 MHz [165] (disabled)
        valid interface combinations:
                 * #{ managed } <= 2048, #{ AP, mesh point } <= 8, #{ P2P-client, P2P-GO } <= 1, #{ IBSS } <= 1,
                   total <= 2048, #channels <= 1, STA/AP BI must match, radar detect widths: { 20 MHz (no HT), 20 MHz, 40 MHz }

        HT Capability overrides:
                 * MCS: ff ff ff ff ff ff ff ff ff ff
                 * maximum A-MSDU length
                 * supported channel width
                 * short GI for 40 MHz
                 * max A-MPDU length exponent
                 * min MPDU start spacing
Wiphy phy1
        max # scan SSIDs: 4
        max scan IEs length: 2261 bytes
        max # sched scan SSIDs: 0
        max # match sets: 0
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Retry short limit: 7
        Retry long limit: 4
        Coverage class: 0 (up to 0m)
        Device supports AP-side u-APSD.
        Device supports T-DLS.
        Available Antennas: TX 0x3 RX 0x3
        Configured Antennas: TX 0x3 RX 0x3
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * AP/VLAN
                 * monitor
                 * mesh point
                 * P2P-client
                 * P2P-GO
                 * outside context of a BSS
        Band 2:
                Capabilities: 0x11ef
                        RX LDPC
                        HT20/HT40
                        SM Power Save disabled
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 8 usec (0x06)
                HT TX/RX MCS rate indexes supported: 0-15
                Frequencies:
                        * 5180 MHz [36] (20.0 dBm)
                        * 5200 MHz [40] (20.0 dBm)
                        * 5220 MHz [44] (20.0 dBm)
                        * 5240 MHz [48] (20.0 dBm)
                        * 5260 MHz [52] (20.0 dBm) (radar detection)
                        * 5280 MHz [56] (20.0 dBm) (radar detection)
                        * 5300 MHz [60] (20.0 dBm) (radar detection)
                        * 5320 MHz [64] (20.0 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)
                        * 5745 MHz [149] (disabled)
                        * 5765 MHz [153] (disabled)
                        * 5785 MHz [157] (disabled)
                        * 5805 MHz [161] (disabled)
                        * 5825 MHz [165] (disabled)
        valid interface combinations:
                 * #{ managed } <= 2048, #{ AP, mesh point } <= 8, #{ P2P-client, P2P-GO } <= 1, #{ IBSS } <= 1,
                   total <= 2048, #channels <= 1, STA/AP BI must match, radar detect widths: { 20 MHz (no HT), 20 MHz, 40 MHz }

        HT Capability overrides:
                 * MCS: ff ff ff ff ff ff ff ff ff ff
                 * maximum A-MSDU length
                 * supported channel width
                 * short GI for 40 MHz
                 * max A-MPDU length exponent
                 * min MPDU start spacing
Wiphy phy0
        max # scan SSIDs: 4
        max scan IEs length: 2257 bytes
        max # sched scan SSIDs: 0
        max # match sets: 0
        max # scan plans: 1
        max scan plan interval: -1
        max scan plan iterations: 0
        Retry short limit: 7
        Retry long limit: 4
        Coverage class: 0 (up to 0m)
        Device supports AP-side u-APSD.
        Device supports T-DLS.
        Available Antennas: TX 0x3 RX 0x3
        Configured Antennas: TX 0x3 RX 0x3
        Supported interface modes:
                 * IBSS
                 * managed
                 * AP
                 * AP/VLAN
                 * monitor
                 * mesh point
                 * P2P-client
                 * P2P-GO
                 * outside context of a BSS
        Band 1:
                Capabilities: 0x11ef
                        RX LDPC
                        HT20/HT40
                        SM Power Save disabled
                        RX HT20 SGI
                        RX HT40 SGI
                        TX STBC
                        RX STBC 1-stream
                        Max AMSDU length: 3839 bytes
                        DSSS/CCK HT40
                Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
                Minimum RX AMPDU time spacing: 8 usec (0x06)
                HT TX/RX MCS rate indexes supported: 0-15
                Frequencies:
                        * 2412 MHz [1] (20.0 dBm)
                        * 2417 MHz [2] (20.0 dBm)
                        * 2422 MHz [3] (20.0 dBm)
                        * 2427 MHz [4] (20.0 dBm)
                        * 2432 MHz [5] (20.0 dBm)
                        * 2437 MHz [6] (20.0 dBm)
                        * 2442 MHz [7] (20.0 dBm)
                        * 2447 MHz [8] (20.0 dBm)
                        * 2452 MHz [9] (20.0 dBm)
                        * 2457 MHz [10] (20.0 dBm)
                        * 2462 MHz [11] (20.0 dBm)
                        * 2467 MHz [12] (20.0 dBm)
                        * 2472 MHz [13] (20.0 dBm)
                        * 2484 MHz [14] (disabled)
        valid interface combinations:
                 * #{ managed } <= 2048, #{ AP, mesh point } <= 8, #{ P2P-client, P2P-GO } <= 1, #{ IBSS } <= 1,
                   total <= 2048, #channels <= 1, STA/AP BI must match, radar detect widths: { 20 MHz (no HT), 20 MHz, 40 MHz }

        HT Capability overrides:
                 * MCS: ff ff ff ff ff ff ff ff ff ff
                 * maximum A-MSDU length
                 * supported channel width
                 * short GI for 40 MHz
                 * max A-MPDU length exponent
                 * min MPDU start spacing
4

Using an AR9582 radio for these tasks is not really surprising as it's quite likely that them OEM firmware also uses it for constant channel sweeps for DFS events, to reduce the downtime of the actively used radio whenever a DFS event occurs (e.g. Linksys does the same with their WRT3200ACM/ WRT32x).

5

Ok, so I've probably configured the MR18 as fast as it'll go already by using HT40 mode on all radios.

I'll probably set radio0 and radio1 SSIDs to match my router to allow router/AP hopping by Wi-Fi client devices, and leave radio2 as is, maybe it can be a management-over-Wi-Fi option if I need to configure the LAN static IP when I don't have a computer with Ethernet.