Terrible wireless download speed on WR940N v5

Hi all,
After flashing LEDE, I found that the best download speed I can get is about 50~55Mbps (upload is around 90Mbps). Did anyone experience the same issue?

dmesg output:

[    0.000000] Linux version 4.4.71 (buildbot@builds-02.infra.lede-project.org) (gcc version 5.4.0 (LEDE GCC 5.4.0 r3101-bce140e) ) #0 Wed Jun 7 19:24:41 2017
[    0.000000] MyLoader: sysp=8f62bd02, boardp=af7ead94, parts=5440c717
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 00019750 (MIPS 74Kc)
[    0.000000] SoC: Qualcomm Atheros TP9343 rev 0
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 02000000 @ 00000000 (usable)
[    0.000000] Initrd not found or empty - disabling initrd
[    0.000000] No valid device tree found, continuing without
[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000000000000-0x0000000001ffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x0000000001ffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000001ffffff]
[    0.000000] On node 0 totalpages: 8192
[    0.000000] free_area_init_node: node 0, pgdat 803d04d0, node_mem_map 81000000
[    0.000000]   Normal zone: 64 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 8192 pages, LIFO batch:0
[    0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[    0.000000] Primary data cache 32kB, 4-way, VIPT, cache aliases, linesize 32 bytes
[    0.000000] pcpu-alloc: s0 r0 d32768 u32768 alloc=1*32768
[    0.000000] pcpu-alloc: [0] 0
[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 8128
[    0.000000] Kernel command line:  board=TL-WR940N-v4  console=ttyS0,115200 rootfstype=squashfs,jffs2 noinitrd
[    0.000000] PID hash table entries: 128 (order: -3, 512 bytes)
[    0.000000] Dentry cache hash table entries: 4096 (order: 2, 16384 bytes)
[    0.000000] Inode-cache hash table entries: 2048 (order: 1, 8192 bytes)
[    0.000000] Writing ErrCtl register=00000000
[    0.000000] Readback ErrCtl register=00000000
[    0.000000] Memory: 27864K/32768K available (3073K kernel code, 163K rwdata, 412K rodata, 312K init, 205K bss, 4904K reserved, 0K cma-reserved)
[    0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[    0.000000] NR_IRQS:51
[    0.000000] Clocks: CPU:750.000MHz, DDR:400.000MHz, AHB:250.000MHz, Ref:25.000MHz
[    0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 5096694524 ns
[    0.000007] sched_clock: 32 bits at 375MHz, resolution 2ns, wraps every 5726622718ns
[    0.008223] Calibrating delay loop... 373.55 BogoMIPS (lpj=1867776)
[    0.071104] pid_max: default: 32768 minimum: 301
[    0.076089] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.083072] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.092927] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.103350] futex hash table entries: 256 (order: -1, 3072 bytes)
[    0.110917] NET: Registered protocol family 16
[    0.116995] MIPS: machine is TP-LINK TL-WR940N v4
[    0.558250] Can't analyze schedule() prologue at 800670bc
[    0.573591] clocksource: Switched to clocksource MIPS
[    0.580072] NET: Registered protocol family 2
[    0.585569] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[    0.592926] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[    0.599696] TCP: Hash tables configured (established 1024 bind 1024)
[    0.606513] UDP hash table entries: 256 (order: 0, 4096 bytes)
[    0.612685] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[    0.619623] NET: Registered protocol family 1
[    0.624289] PCI: CLS 0 bytes, default 32
[    0.628728] Crashlog allocated RAM at address 0x1f00000
[    0.648540] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    0.654747] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[    0.667510] io scheduler noop registered
[    0.671642] io scheduler deadline registered (default)
[    0.677326] Serial: 8250/16550 driver, 16 ports, IRQ sharing enabled
[    0.686543] console [ttyS0] disabled
[    0.710418] serial8250.0: ttyS0 at MMIO 0x18020000 (irq = 11, base_baud = 1562500) is a 16550A
[    0.719528] console [ttyS0] enabled
[    0.727088] bootconsole [early0] disabled
[    0.740744] m25p80 spi0.0: found gd25q32, expected m25p80
[    0.746404] m25p80 spi0.0: gd25q32 (4096 Kbytes)
[    0.752483] 5 tp-link partitions found on MTD device spi0.0
[    0.758287] Creating 5 MTD partitions on "spi0.0":
[    0.763238] 0x000000000000-0x000000020000 : "u-boot"
[    0.769765] 0x000000020000-0x000000152fb4 : "kernel"
[    0.776553] 0x000000152fb4-0x0000003f0000 : "rootfs"
[    0.783233] mtd: device 2 (rootfs) set to be root filesystem
[    0.789202] 1 squashfs-split partitions found on MTD device rootfs
[    0.795609] 0x000000380000-0x0000003f0000 : "rootfs_data"
[    0.802828] 0x0000003f0000-0x000000400000 : "art"
[    0.809370] 0x000000020000-0x0000003f0000 : "firmware"
[    0.832881] libphy: ag71xx_mdio: probed
[    1.425678] ag71xx ag71xx.0: connected to PHY at ag71xx-mdio.1:04 [uid=004dd042, driver=Generic PHY]
[    1.435771] eth0: Atheros AG71xx at 0xb9000000, irq 4, mode:MII
[    2.025449] ag71xx-mdio.1: Found an AR934X built-in switch
[    2.067666] eth1: Atheros AG71xx at 0xba000000, irq 5, mode:GMII
[    2.076234] NET: Registered protocol family 10
[    2.085741] NET: Registered protocol family 17
[    2.090406] bridge: automatic filtering via arp/ip/ip6tables has been deprecated. Update your scripts to load br_netfilter if you need this.
[    2.103604] 8021q: 802.1Q VLAN Support v1.8
[    2.114812] VFS: Mounted root (squashfs filesystem) readonly on device 31:2.
[    2.124442] Freeing unused kernel memory: 312K (803f2000 - 80440000)
[    3.102984] init: Console is alive
[    3.106809] init: - watchdog -
[    3.871823] kmodloader: loading kernel modules from /etc/modules-boot.d/*
[    3.931274] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[    3.949849] init: - preinit -
[    4.428742] IPv6: ADDRCONF(NETDEV_UP): eth1: link is not ready
[    4.454949] random: procd: uninitialized urandom read (4 bytes read, 7 bits of entropy available)
[    6.524954] eth1: link up (1000Mbps/Full duplex)
[    6.529761] IPv6: ADDRCONF(NETDEV_CHANGE): eth1: link becomes ready
[    7.706966] jffs2: notice: (374) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
[    7.724600] mount_root: switching to jffs2 overlay
[    7.737883] urandom-seed: Seeding with /etc/urandom.seed
[    7.909994] eth1: link down
[    7.923528] procd: - early -
[    7.927635] procd: - watchdog -
[    8.541741] procd: - ubus -
[    8.646382] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.657376] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.667217] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.676575] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.686275] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.695639] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.705502] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.715011] random: ubusd: uninitialized urandom read (4 bytes read, 14 bits of entropy available)
[    8.724739] procd: - init -
[    9.053024] kmodloader: loading kernel modules from /etc/modules.d/*
[    9.063894] ip6_tables: (C) 2000-2006 Netfilter Core Team
[    9.080816] Loading modules backported from Linux version wt-2017-01-31-0-ge882dff19e7f
[    9.089152] Backport generated by backports.git backports-20160324-13-g24da7d3c
[    9.099860] ip_tables: (C) 2000-2006 Netfilter Core Team
[    9.113197] nf_conntrack version 0.5.0 (440 buckets, 1760 max)
[    9.152657] xt_time: kernel timezone is -0000
[    9.215901] PPP generic driver version 2.4.2
[    9.222743] NET: Registered protocol family 24
[    9.273435] ath: EEPROM regdomain: 0x0
[    9.273456] ath: EEPROM indicates default country code should be used
[    9.273463] ath: doing EEPROM country->regdmn map search
[    9.273481] ath: country maps to regdmn code: 0x3a
[    9.273490] ath: Country alpha2 being used: US
[    9.273497] ath: Regpair used: 0x3a
[    9.285343] ieee80211 phy0: Selected rate control algorithm 'minstrel_ht'
[    9.291731] ieee80211 phy0: Atheros AR9561 Rev:0 mem=0xb8100000, irq=47
[    9.386431] kmodloader: done loading kernel modules from /etc/modules.d/*
[   10.237342] random: jshn: uninitialized urandom read (4 bytes read, 16 bits of entropy available)
[   15.663775] device eth1 entered promiscuous mode
[   15.681855] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
[   16.584456] ath: EEPROM regdomain: 0x809e
[   16.588606] ath: EEPROM indicates we should expect a country code
[   16.594958] ath: doing EEPROM country->regdmn map search
[   16.600442] ath: country maps to regdmn code: 0x50
[   16.605403] ath: Country alpha2 being used: TW
[   16.609990] ath: Regpair used: 0x50
[   16.613598] ath: regdomain 0x809e dynamically updated by user
[   17.798508] eth1: link up (1000Mbps/Full duplex)
[   17.823719] br-lan: port 1(eth1) entered forwarding state
[   17.829363] br-lan: port 1(eth1) entered forwarding state
[   17.853706] IPv6: ADDRCONF(NETDEV_CHANGE): br-lan: link becomes ready
[   18.466982] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[   18.496792] device wlan0 entered promiscuous mode
[   18.501918] br-lan: port 2(wlan0) entered forwarding state
[   18.507672] br-lan: port 2(wlan0) entered forwarding state
[   18.835706] eth0: link up (100Mbps/Full duplex)
[   18.862821] br-lan: port 2(wlan0) entered disabled state
[   19.287190] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   19.293974] br-lan: port 2(wlan0) entered forwarding state
[   19.299694] br-lan: port 2(wlan0) entered forwarding state
[   19.768903] pppoe-wan: renamed from ppp0
[   19.823647] br-lan: port 1(eth1) entered forwarding state
[   21.293626] br-lan: port 2(wlan0) entered forwarding state
[   36.008810] random: nonblocking pool is initialized

/etc/config/wireless setting:

config wifi-device 'radio0'
	option type 'mac80211'
	option hwmode '11n'
	option short_preamble '1'
	option path 'platform/qca956x_wmac'
	option txpower '26'
	option country 'TW'
	option noscan '1'
	option htmode 'HT40'
	option channel '1'
	option wmm '1'
	option short_gi_40 '1'
	option nohwcrypt '1'

config wifi-iface 'default_radio0'
	option device 'radio0'
	option network 'lan'
	option mode 'ap'
	option ssid 'xxxxx'
	option encryption 'psk2+ccmp'
	option key '12341234'
	option disassoc_low_ack '0'

iwinfo output:

wlan0     ESSID: "xxxx"
          Access Point: 50:C7:BF:C0:69:7C
          Mode: Master  Channel: 1 (2.412 GHz)
          Tx-Power: 22 dBm  Link Quality: 60/70
          Signal: -50 dBm  Noise: -95 dBm
          Bit Rate: 124.6 MBit/s
          Encryption: WPA2 PSK (CCMP)
          Type: nl80211  HW Mode(s): 802.11bgn
          Hardware: unknown [Generic MAC80211]
          TX power offset: unknown
          Frequency offset: unknown
          Supports VAPs: yes  PHY name: phy0

Have the ame router w940n v5, the lede version for this model is available ? or what version did you use?

B.R.

How did you test the download speed?