@Xkeeper (Marek Fedorco) posted a new topic, subject "Hostapd AC signal low". It read:

   Hello,
    
    I'm having trouble with a extremly low wifi signal on a newly built router based on `PC Engines APU.2D4` system with a  
    `MikroTik R11e-5HacD miniPCI-e karta 802.11ac, 2 x MMCX, Atheros (5 GHz)` card & a 9dBi omnidirectional antenna.
    
    This is what I'm getting being just 4.5 meters away from the router.  
    MUGEN is my ssid:
    
    low signal383×710 13.5 KB
    
    Compare it to my upstairs neighbor TypeR ssid. He is running something called "Compal modem" that he received from his provider. This device is located one floor above me, 10 meters away and trough a concrete ceiling.
    
    My hostapd config:
    [code] 
        interface=wlp4s0
        driver=nl80211
        logger_syslog=-1
        logger_syslog_level=2
        logger_stdout=-1
        logger_stdout_level=2
        debug=4
        channel=44
        ieee80211d=1
        country_code=SK
        hw_mode=a
        macaddr_acl=0
        auth_algs=3
        eapol_key_index_workaround=0
        eap_server=0
        wpa=2
        ssid=MUGEN
        wpa_passphrase=whatever
        wpa_key_mgmt=WPA-PSK
        wpa_pairwise=CCMP
        eapol_version=1
        wme_enabled=1
        wmm_enabled=1
        wmm_ac_bk_cwmin=4
        wmm_ac_bk_cwmax=10
        wmm_ac_bk_aifs=7
        wmm_ac_bk_txop_limit=0
        wmm_ac_bk_acm=0
        wmm_ac_bk_cwmin=4
        wmm_ac_bk_cwmax=10
        wmm_ac_bk_aifs=7
        wmm_ac_bk_txop_limit=0
        wmm_ac_bk_acm=0
        wmm_ac_be_aifs=3
        wmm_ac_be_cwmin=4
        wmm_ac_be_cwmax=10
        wmm_ac_be_txop_limit=0
        wmm_ac_be_acm=0
        wmm_ac_vi_aifs=2
        wmm_ac_vi_cwmin=3
        wmm_ac_vi_cwmax=4
        wmm_ac_vi_txop_limit=94
        wmm_ac_vi_acm=0
        wmm_ac_vo_aifs=2
        wmm_ac_vo_cwmin=2
        wmm_ac_vo_cwmax=3
        wmm_ac_vo_txop_limit=47
        wmm_ac_vo_acm=0
        ieee80211n=1
        ieee80211ac=1
        ht_capab=[HT40+][SHORT-GI-40][DSSS_CCK-40][MAX-AMSDU-3839]
        vht_capab=[MAX-MPDU-11454][MAX-A-MPDU-LEN-EXP0][SHORT-GI-80]
        vht_oper_chwidth=1
        vht_oper_centr_freq_seg0_idx=42
        #vht_oper_centr_freq_seg1_idx=159
        
    [/code]
    
    iw outputs:
    [code] 
        root@xxx:~# iw wlp4s0 info
        Interface wlp4s0
                ifindex 6
                wdev 0x1
                addr cc:2d:e0:91:19:b3
                ssid MUGEN
                type AP
                wiphy 0
                channel 44 (5220 MHz), width: 80 MHz, center1: 5210 MHz
                txpower 20.00 dBm
                multicast TXQ:
                        qsz-byt qsz-pkt flows   drops   marks   overlmt hashcol tx-bytes        tx-packets
                        0       0       3455465 0       0       0       0       962880010               3455465
        
    [/code]
    [code] 
        root@xxx:~# iw list
        Wiphy phy0
                max # scan SSIDs: 16
                max scan IEs length: 199 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 RSN-IBSS.
                Device supports AP-side u-APSD.
                Supported Ciphers:
                        * WEP40 (00-0f-ac:1)
                        * WEP104 (00-0f-ac:5)
                        * TKIP (00-0f-ac:2)
                        * CCMP-128 (00-0f-ac:4)
                        * CMAC (00-0f-ac:6)
                        * CMAC-256 (00-0f-ac:13)
                        * GMAC-128 (00-0f-ac:11)
                        * GMAC-256 (00-0f-ac:12)
                Available Antennas: TX 0x3 RX 0x3
                Configured Antennas: TX 0x3 RX 0x3
                Supported interface modes:
                         * managed
                         * AP
                         * monitor
                         * mesh point
                Band 2:
                        Capabilities: 0x19ef
                                RX LDPC
                                HT20/HT40
                                SM Power Save disabled
                                RX HT20 SGI
                                RX HT40 SGI
                                TX STBC
                                RX STBC 1-stream
                                Max AMSDU length: 7935 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
                        VHT Capabilities (0x338001b2):
                                Max MPDU length: 11454
                                Supported Channel Width: neither 160 nor 80+80
                                RX LDPC
                                short GI (80 MHz)
                                TX STBC
                                RX antenna pattern consistency
                                TX antenna pattern consistency
                        VHT RX MCS set:
                                1 streams: MCS 0-9
                                2 streams: MCS 0-9
                                3 streams: not supported
                                4 streams: not supported
                                5 streams: not supported
                                6 streams: not supported
                                7 streams: not supported
                                8 streams: not supported
                        VHT RX highest supported: 0 Mbps
                        VHT TX MCS set:
                                1 streams: MCS 0-9
                                2 streams: MCS 0-9
                                3 streams: not supported
                                4 streams: not supported
                                5 streams: not supported
                                6 streams: not supported
                                7 streams: not supported
                                8 streams: not supported
                        VHT TX highest supported: 0 Mbps
                        Bitrates (non-HT):
                                * 6.0 Mbps
                                * 9.0 Mbps
                                * 12.0 Mbps
                                * 18.0 Mbps
                                * 24.0 Mbps
                                * 36.0 Mbps
                                * 48.0 Mbps
                                * 54.0 Mbps
                        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) (no IR, radar detection)
                                * 5280 MHz [56] (20.0 dBm) (no IR, radar detection)
                                * 5300 MHz [60] (20.0 dBm) (no IR, radar detection)
                                * 5320 MHz [64] (20.0 dBm) (no IR, radar detection)
                                * 5500 MHz [100] (23.0 dBm) (no IR, radar detection)
                                * 5520 MHz [104] (23.0 dBm) (no IR, radar detection)
                                * 5540 MHz [108] (23.0 dBm) (no IR, radar detection)
                                * 5560 MHz [112] (23.0 dBm) (no IR, radar detection)
                                * 5580 MHz [116] (23.0 dBm) (no IR, radar detection)
                                * 5600 MHz [120] (23.0 dBm) (no IR, radar detection)
                                * 5620 MHz [124] (23.0 dBm) (no IR, radar detection)
                                * 5640 MHz [128] (23.0 dBm) (no IR, radar detection)
                                * 5660 MHz [132] (23.0 dBm) (no IR, radar detection)
                                * 5680 MHz [136] (23.0 dBm) (no IR, radar detection)
                                * 5700 MHz [140] (23.0 dBm) (no IR, radar detection)
                                * 5720 MHz [144] (disabled)
                                * 5745 MHz [149] (disabled)
                                * 5765 MHz [153] (disabled)
                                * 5785 MHz [157] (disabled)
                                * 5805 MHz [161] (disabled)
                                * 5825 MHz [165] (disabled)
                                * 5845 MHz [169] (disabled)
                                * 5865 MHz [173] (disabled)
                Supported commands:
                         * new_interface
                         * set_interface
                         * new_key
                         * start_ap
                         * new_station
                         * new_mpath
                         * set_mesh_config
                         * set_bss
                         * authenticate
                         * associate
                         * deauthenticate
                         * disassociate
                         * join_ibss
                         * join_mesh
                         * remain_on_channel
                         * set_tx_bitrate_mask
                         * frame
                         * frame_wait_cancel
                         * set_wiphy_netns
                         * set_channel
                         * set_wds_peer
                         * probe_client
                         * set_noack_map
                         * register_beacons
                         * start_p2p_device
                         * set_mcast_rate
                         * connect
                         * disconnect
                         * channel_switch
                         * set_qos_map
                         * set_multicast_to_unicast
                Supported TX frame types:
                         * IBSS: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * managed: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * AP: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * AP/VLAN: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * mesh point: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * P2P-client: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * P2P-GO: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                         * P2P-device: 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80 0x90 0xa0 0xb0 0xc0 0xd0 0xe0 0xf0
                Supported RX frame types:
                         * IBSS: 0x40 0xb0 0xc0 0xd0
                         * managed: 0x40 0xd0
                         * AP: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
                         * AP/VLAN: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
                         * mesh point: 0xb0 0xc0 0xd0
                         * P2P-client: 0x40 0xd0
                         * P2P-GO: 0x00 0x20 0x40 0xa0 0xb0 0xc0 0xd0
                         * P2P-device: 0x40 0xd0
                software interface modes (can always be added):
                         * monitor
                valid interface combinations:
                         * #{ AP, mesh point } <= 8, #{ managed } <= 1,
                           total <= 8, #channels <= 1, STA/AP BI must match
                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
                Device supports TX status socket option.
                Device supports HT-IBSS.
                Device supports SAE with AUTHENTICATE command
                Device supports scan flush.
                Device supports AP scan.
                Device supports per-vif TX power setting
                Driver supports full state transitions for AP/GO clients
                Driver supports a userspace MPM
                Driver/device bandwidth changes during BSS lifetime (AP/GO mode)
                Device supports static SMPS
                Device supports configuring vdev MAC-addr on create.
                Supported extended features:
                        * [ VHT_IBSS ]: VHT-IBSS
                        * [ RRM ]: RRM
                        * [ SET_SCAN_DWELL ]: scan dwell setting
                        * [ FILS_STA ]: STA FILS (Fast Initial Link Setup)
                        * [ CQM_RSSI_LIST ]: multiple CQM_RSSI_THOLD records
                        * [ CONTROL_PORT_OVER_NL80211 ]: control port over nl80211
                        * [ TXQS ]: FQ-CoDel-enabled intermediate TXQs
        
    [/code]
    
    Please help, I have no idea how to solve this.

So @bluewavenet (Bluewavenet) replied

    I have not used this card but with similar I found using two antennas was required. With just a single antenna, the driver detects the missing one and dramatically reduces power.  
    You say you only have one antenna......

So @Xkeeper (Marek Fedorco) replied

    Yes that is correct. I will get a second one to test.
    
    Is there a 5Ghz AC antenna that you'd recommend ?
    
    Thank you.

To which @bluewavenet (Bluewavenet) replied

    Where did you get the one you have? They usually come with a connector and pigtail. It is probably best to have a matching pair.

After which, @Xkeeper (Marek Fedorco) added

    Some local supplier. I will order second one will see if it helps.  
    I have also found this one, if the first doesnt work:  
    https://www.wifi-shop24.com/CONEXUM-24/5GHz-2x2MIMO-Omni-Antenna-Band-Filter-ac/ax

So @bluewavenet (Bluewavenet) replied

    That does not look suitable for the PC Engines matthewspatricia@example.org.  
    You need something like this (or maybe not - see edit):  
    amazon.co.uk
    
    ### WayinTop 2Set 8dBi 2.4GHz 5GHz Dual Band Wireless: Amazon.co.uk: Electronics
    
    Shop WayinTop 2Set 8dBi 2.4GHz 5GHz Dual Band Wireless Network WiFi RP-SMA Male Antenna + 20cm U.FL/IPEX to RP-SMA Female Pigtail Cable for Mini PCIe Card Router Repeater Desktop PC FPV UAV Drone PS4. Free delivery and returns on eligible orders.
    
    **£9.99**
    
      
    **EDIT** This card has mmcx connectors (fairly rare) so you need special pigtails:  
    amazon.co.uk
    
    ### SMA Female to MMCX Male 10CM Right Angle RG316 Cable: Amazon.co.uk: Electronics
    
    Shop SMA Female to MMCX Male 10CM Right Angle RG316 Cable MMCX to SMA Extension Assembly Cable for WiFi Antenna Pigtail QAV250 H210 FPV Racing Pack of 2. Free delivery and returns on eligible orders.
    
    **£5.88**

So @Xkeeper (Marek Fedorco) replied

    Hello, short update, I have purchased second antenna same as the first. It did not help one bit.
    
    I'm thinking that maybe there is a difference between 5Ghz and 5Ghz rated for AC.
    
    So now I will try to find a pair that is AC rated.


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