The TL-MR6400 v3 is basically the same hardware and flash layout as the TL-MR3420 v5 with the exception of the LTE modem.
I have the openwrt factory image for the MR3420 v5 booting fine on the MR6400 v3 , both ethernet and wifi also working without any issues.
I just can not get the LTE modem to work. It is recognized in the boot log, however running "uqmi -d /dev/ttyUSB3 --get-signal-info" results in the console freezing up. After doing ctrl^c I then get a message back from uqmi "Failed to connect to service"
Heres the dmesg log:
U-Boot 1.1.3 (Nov 16 2018 - 15:45:52)
Board: Ralink APSoC DRAM: 64 MB
relocate_code Pointer at: 83fb4000
******************************
Software System Reset Occurred
******************************
gpiomode1 55054404.
gpiomode2 05550555.
######GPIO CTRL 1 for GPIO 32~64 OUTPUT tmp(0x00001fa0)#####
######GPIO CTRL 1 for GPIO 32~64 INPUT tmp(0x00001fa0)#####
flash manufacture id: c8, device id 40 17
find flash: GD25Q64B
============================================
Ralink UBoot Version: 4.3.0.0
--------------------------------------------
ASIC 7628_MP (Port5<->None)
DRAM component: 512 Mbits DDR, width 16
DRAM bus: 16 bit
Total memory: 64 MBytes
Flash component: SPI Flash
Date:Nov 16 2018 Time:15:45:52
============================================
icache: sets:512, ways:4, linesz:32 ,total:65536
dcache: sets:256, ways:4, linesz:32 ,total:32768
##### The CPU freq = 580 MHZ ####
estimate memory size =64 Mbytes
RESET MT7628 PHY!!!!!!
continue to starting system. 0
disable switch phyport...
3: System Boot system code via Flash.(0xbc020000)
do_bootm:argc=2, addr=0xbc020000
## Booting image at bc020000 ...
Uncompressing Kernel Image ... OK
No initrd
## Transferring control to Linux (at address 80000000) ...
## Giving linux memsize in MB, 64
Starting kernel ...
[ 0.000000] Linux version 4.14.131 (user@build-vm) (gcc version 7.3.0 (OpenWrt GCC 7.3.0 r7808-ef686b7292)) #0 Thu Jun 27 12:18:52 2019
[ 0.000000] Board has DDR2
[ 0.000000] Analog PMU set to hw control
[ 0.000000] Digital PMU set to hw control
[ 0.000000] SoC Type: MediaTek MT7628AN ver:1 eco:2
[ 0.000000] bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 00019655 (MIPS 24KEc)
[ 0.000000] MIPS: machine is TP-Link TL-MR3420 v5
[ 0.000000] Determined physical RAM map:
[ 0.000000] memory: 04000000 @ 00000000 (usable)
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000000000000-0x0000000003ffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x0000000003ffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000003ffffff]
[ 0.000000] random: get_random_bytes called from start_kernel+0x90/0x478 with crng_init=0
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 16256
[ 0.000000] Kernel command line: console=ttyS0,115200 rootfstype=squashfs,jffs2
[ 0.000000] PID hash table entries: 256 (order: -2, 1024 bytes)
[ 0.000000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
[ 0.000000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
[ 0.000000] Writing ErrCtl register=0006297e
[ 0.000000] Readback ErrCtl register=0006297e
[ 0.000000] Memory: 60044K/65536K available (3427K kernel code, 172K rwdata, 824K rodata, 176K init, 200K bss, 5492K reserved, 0K cma-reserved)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.000000] NR_IRQS: 256
[ 0.000000] intc: using register map from devicetree
[ 0.000000] CPU Clock: 580MHz
[ 0.000000] timer_probe: no matching timers found
[ 0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 6590553264 ns
[ 0.000010] sched_clock: 32 bits at 290MHz, resolution 3ns, wraps every 7405115902ns
[ 0.007540] Calibrating delay loop... 385.84 BogoMIPS (lpj=1929216)
[ 0.073492] pid_max: default: 32768 minimum: 301
[ 0.078163] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.084505] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.096409] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.105894] futex hash table entries: 256 (order: -1, 3072 bytes)
[ 0.111844] pinctrl core: initialized pinctrl subsystem
[ 0.117361] NET: Registered protocol family 16
[ 0.145620] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.151256] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.156777] mt7621_gpio 10000600.gpio: registering 32 gpios
[ 0.166354] clocksource: Switched to clocksource MIPS
[ 0.172337] NET: Registered protocol family 2
[ 0.177350] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.184038] TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
[ 0.190221] TCP: Hash tables configured (established 1024 bind 1024)
[ 0.196480] UDP hash table entries: 256 (order: 0, 4096 bytes)
[ 0.202082] UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
[ 0.208400] NET: Registered protocol family 1
[ 0.215789] Crashlog allocated RAM at address 0x3f00000
[ 0.222404] workingset: timestamp_bits=30 max_order=14 bucket_order=0
[ 0.233839] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 0.239458] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[ 0.258574] io scheduler noop registered
[ 0.262303] io scheduler deadline registered (default)
[ 0.268206] Serial: 8250/16550 driver, 3 ports, IRQ sharing disabled
[ 0.275365] console [ttyS0] disabled
[ 0.278865] 10000c00.uartlite: ttyS0 at MMIO 0x10000c00 (irq = 28, base_baud = 2500000) is a 16550A
[ 0.287578] console [ttyS0] enabled
[ 0.287578] console [ttyS0] enabled
[ 0.294578] bootconsole [early0] disabled
[ 0.294578] bootconsole [early0] disabled
[ 0.303159] cacheinfo: Failed to find cpu0 device node
[ 0.308407] cacheinfo: Unable to detect cache hierarchy for CPU 0
[ 0.315229] spi-mt7621 10000b00.spi: sys_freq: 193333333
[ 0.327076] m25p80 spi0.0: gd25q64 (8192 Kbytes)
[ 0.331807] 4 fixed-partitions partitions found on MTD device spi0.0
[ 0.338263] Creating 4 MTD partitions on "spi0.0":
[ 0.343128] 0x000000000000-0x000000020000 : "boot"
[ 0.348864] 0x000000020000-0x0000007c0000 : "firmware"
[ 0.405055] 2 tplink-fw partitions found on MTD device firmware
[ 0.411098] 0x000000020000-0x00000018a6c7 : "kernel"
[ 0.417052] 0x00000018a6c8-0x0000007c0000 : "rootfs"
[ 0.422801] mtd: device 3 (rootfs) set to be root filesystem
[ 0.430093] 1 squashfs-split partitions found on MTD device rootfs
[ 0.436427] 0x000000560000-0x0000007c0000 : "rootfs_data"
[ 0.442763] 0x0000007c0000-0x0000007d0000 : "config"
[ 0.448645] 0x0000007d0000-0x000000800000 : "factory"
[ 0.455208] libphy: Fixed MDIO Bus: probed
[ 0.471618] rt3050-esw 10110000.esw: link changed 0x00
[ 0.478373] mtk_soc_eth 10100000.ethernet eth0: mediatek frame engine at 0xb0100000, irq 5
[ 0.488417] NET: Registered protocol family 10
[ 0.496865] Segment Routing with IPv6
[ 0.500684] NET: Registered protocol family 17
[ 0.505229] 8021q: 802.1Q VLAN Support v1.8
[ 0.521782] VFS: Mounted root (squashfs filesystem) readonly on device 31:3.
[ 0.529960] Freeing unused kernel memory: 176K
[ 0.534464] This architecture does not have kernel memory protection.
[ 1.868265] init: Console is alive
[ 1.871947] init: - watchdog -
[ 2.296358] random: fast init done
[ 4.119009] kmodloader: loading kernel modules from /etc/modules-boot.d/*
[ 4.296264] usbcore: registered new interface driver usbfs
[ 4.302002] usbcore: registered new interface driver hub
[ 4.307521] usbcore: registered new device driver usb
[ 4.318694] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 4.334011] SCSI subsystem initialized
[ 4.343407] ehci-platform: EHCI generic platform driver
[ 4.359044] phy phy-10120000.usbphy.0: remote usb device wakeup disabled
[ 4.365844] phy phy-10120000.usbphy.0: UTMI 16bit 30MHz
[ 4.371177] ehci-platform 101c0000.ehci: EHCI Host Controller
[ 4.377046] ehci-platform 101c0000.ehci: new USB bus registered, assigned bus number 1
[ 4.385195] ehci-platform 101c0000.ehci: irq 26, io mem 0x101c0000
[ 4.416397] ehci-platform 101c0000.ehci: USB 2.0 started, EHCI 1.00
[ 4.423704] hub 1-0:1.0: USB hub found
[ 4.427954] hub 1-0:1.0: 1 port detected
[ 4.434181] ehci-pci: EHCI PCI platform driver
[ 4.442034] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 4.449892] ohci-platform: OHCI generic platform driver
[ 4.455435] ohci-platform 101c1000.ohci: Generic Platform OHCI controller
[ 4.462422] ohci-platform 101c1000.ohci: new USB bus registered, assigned bus number 2
[ 4.470572] ohci-platform 101c1000.ohci: irq 26, io mem 0x101c1000
[ 4.551285] hub 2-0:1.0: USB hub found
[ 4.555472] hub 2-0:1.0: 1 port detected
[ 4.562600] uhci_hcd: USB Universal Host Controller Interface driver
[ 4.587488] usbcore: registered new interface driver usb-storage
[ 4.596070] usbcore: registered new interface driver uas
[ 4.602290] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[ 4.620142] init: - preinit -
[ 5.399243] usb 1-1: new high-speed USB device number 2 using ehci-platform
[ 5.691388] random: procd: uninitialized urandom read (4 bytes read)
[ 5.703139] usb-storage 1-1:1.5: USB Mass Storage device detected
[ 5.725789] scsi host0: usb-storage 1-1:1.5
[ 6.011057] rt3050-esw 10110000.esw: link changed 0x00
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
[ 6.738910] scsi 0:0:0:0: Direct-Access Linux File-Stor Gadget 0318 PQ: 0 ANSI: 2
[ 6.753444] sd 0:0:0:0: [sda] 130048 512-byte logical blocks: (66.6 MB/63.5 MiB)
[ 6.761807] sd 0:0:0:0: [sda] Write Protect is off
[ 6.767432] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 6.786955] sda:
[ 6.798067] sd 0:0:0:0: [sda] Attached SCSI removable disk
[ 9.360882] jffs2: notice: (402) jffs2_build_xattr_subsystem: complete building xattr subsystem, 8 of xdatum (0 unchecked, 5 orphan) and 9 of xref (5 dead, 0 orphan) found.
[ 9.378720] mount_root: switching to jffs2 overlay
[ 9.449646] overlayfs: upper fs does not support tmpfile.
[ 9.461396] urandom-seed: Seeding with /etc/urandom.seed
[ 9.601188] procd: - early -
[ 9.604220] procd: - watchdog -
[ 10.520218] procd: - watchdog -
[ 10.523662] procd: - ubus -
[ 10.835863] random: ubusd: uninitialized urandom read (4 bytes read)
[ 10.915139] random: jshn: uninitialized urandom read (4 bytes read)
[ 10.998688] random: ubusd: uninitialized urandom read (4 bytes read)
[ 11.006730] procd: - init -
Please press Enter to activate this console.
[ 12.224197] kmodloader: loading kernel modules from /etc/modules.d/*
[ 12.247579] tun: Universal TUN/TAP device driver, 1.6
[ 12.289039] gre: GRE over IPv4 demultiplexor driver
[ 12.302627] ip_gre: GRE over IPv4 tunneling driver
[ 12.323814] ip6_gre: GRE over IPv6 tunneling driver
[ 12.377942] ip6_tables: (C) 2000-2006 Netfilter Core Team
[ 12.481617] u32 classifier
[ 12.484372] input device check on
[ 12.488145] Actions configured
[ 12.550856] Mirror/redirect action on
[ 12.674032] usbcore: registered new interface driver cdc_wdm
[ 12.698202] Loading modules backported from Linux version wt-2017-11-01-0-gfe248fc2c180
[ 12.706325] Backport generated by backports.git v4.14-rc2-1-31-g86cf0e5d
[ 12.750862] ip_tables: (C) 2000-2006 Netfilter Core Team
[ 12.789758] nf_conntrack version 0.5.0 (1024 buckets, 4096 max)
[ 13.013081] usbcore: registered new interface driver ums-alauda
[ 13.028007] usbcore: registered new interface driver ums-cypress
[ 13.048014] usbcore: registered new interface driver ums-datafab
[ 13.060662] usbcore: registered new interface driver ums-freecom
[ 13.085714] usbcore: registered new interface driver ums-isd200
[ 13.108217] usbcore: registered new interface driver ums-jumpshot
[ 13.133063] usbcore: registered new interface driver ums-karma
[ 13.148635] usbcore: registered new interface driver ums-sddr09
[ 13.168215] usbcore: registered new interface driver ums-sddr55
[ 13.184148] usbcore: registered new interface driver ums-usbat
[ 13.223606] usbcore: registered new interface driver usbserial
[ 13.229729] usbcore: registered new interface driver usbserial_generic
[ 13.236469] usbserial: USB Serial support registered for generic
[ 13.287778] usbcore: registered new interface driver visor
[ 13.293435] usbserial: USB Serial support registered for Handspring Visor / Palm OS
[ 13.301364] usbserial: USB Serial support registered for Sony Clie 5.0
[ 13.308087] usbserial: USB Serial support registered for Sony Clie 3.5
[ 13.437400] xt_time: kernel timezone is -0000
[ 13.447956] usbcore: registered new interface driver ark3116
[ 13.453794] usbserial: USB Serial support registered for ark3116
[ 13.474467] usbcore: registered new interface driver belkin_sa
[ 13.480579] usbserial: USB Serial support registered for Belkin / Peracom / GoHubs USB Serial Adapter
[ 13.542748] usbcore: registered new interface driver cdc_ether
[ 13.555123] usbcore: registered new interface driver cdc_ncm
[ 13.664148] usbcore: registered new interface driver ch341
[ 13.669899] usbserial: USB Serial support registered for ch341-uart
[ 13.678900] usbcore: registered new interface driver cp210x
[ 13.684649] usbserial: USB Serial support registered for cp210x
[ 13.693868] usbcore: registered new interface driver cypress_m8
[ 13.700058] usbserial: USB Serial support registered for DeLorme Earthmate USB
[ 13.707491] usbserial: USB Serial support registered for HID->COM RS232 Adapter
[ 13.714986] usbserial: USB Serial support registered for Nokia CA-42 V2 Adapter
[ 13.726554] usbcore: registered new interface driver ftdi_sio
[ 13.732481] usbserial: USB Serial support registered for FTDI USB Serial Device
[ 13.743817] usbcore: registered new interface driver garmin_gps
[ 13.750004] usbserial: USB Serial support registered for Garmin GPS usb/tty
[ 13.760624] usbcore: registered new interface driver io_edgeport
[ 13.766924] usbserial: USB Serial support registered for Edgeport 2 port adapter
[ 13.774493] usbserial: USB Serial support registered for Edgeport 4 port adapter
[ 13.782114] usbserial: USB Serial support registered for Edgeport 8 port adapter
[ 13.789720] usbserial: USB Serial support registered for EPiC device
[ 13.805566] usbcore: registered new interface driver keyspan
[ 13.811500] usbserial: USB Serial support registered for Keyspan - (without firmware)
[ 13.819561] usbserial: USB Serial support registered for Keyspan 1 port adapter
[ 13.827113] usbserial: USB Serial support registered for Keyspan 2 port adapter
[ 13.834602] usbserial: USB Serial support registered for Keyspan 4 port adapter
[ 13.880190] usbcore: registered new interface driver mct_u232
[ 13.886129] usbserial: USB Serial support registered for MCT U232
[ 13.895423] usbcore: registered new interface driver mos7720
[ 13.901348] usbserial: USB Serial support registered for Moschip 2 port adapter
[ 13.921605] mt76_wmac 10300000.wmac: ASIC revision: 76280001
[ 14.948355] mt76_wmac 10300000.wmac: Firmware Version: 20151201
[ 14.954377] mt76_wmac 10300000.wmac: Build Time: 20151201183641
[ 14.976360] mt76_wmac 10300000.wmac: firmware init done
[ 15.196068] usbcore: registered new interface driver oti6858
[ 15.202011] usbserial: USB Serial support registered for oti6858
[ 15.284891] usbcore: registered new interface driver pl2303
[ 15.290737] usbserial: USB Serial support registered for pl2303
[ 15.301870] PPP generic driver version 2.4.2
[ 15.309415] NET: Registered protocol family 24
[ 15.318725] qmi_wwan 1-1:1.4: cdc-wdm0: USB WDM device
[ 15.324895] qmi_wwan 1-1:1.4 wwan0: register 'qmi_wwan' at usb-101c0000.ehci-1, WWAN/QMI device, 56:a0:4a:7a:2b:9d
[ 15.335818] usbcore: registered new interface driver qmi_wwan
[ 15.347391] usbcore: registered new interface driver rndis_host
[ 15.369354] usbcore: registered new interface driver sierra
[ 15.375100] usbserial: USB Serial support registered for Sierra USB modem
[ 15.399184] usbcore: registered new interface driver ti_usb_3410_5052
[ 15.405817] usbserial: USB Serial support registered for TI USB 3410 1 port adapter
[ 15.413739] usbserial: USB Serial support registered for TI USB 5052 2 port adapter
[ 15.491241] usbcore: registered new interface driver usb_serial_simple
[ 15.498047] usbserial: USB Serial support registered for carelink
[ 15.504301] usbserial: USB Serial support registered for zio
[ 15.510172] usbserial: USB Serial support registered for funsoft
[ 15.516395] usbserial: USB Serial support registered for flashloader
[ 15.522932] usbserial: USB Serial support registered for google
[ 15.529056] usbserial: USB Serial support registered for libtransistor
[ 15.535756] usbserial: USB Serial support registered for vivopay
[ 15.541982] usbserial: USB Serial support registered for moto_modem
[ 15.548499] usbserial: USB Serial support registered for motorola_tetra
[ 15.555291] usbserial: USB Serial support registered for novatel_gps
[ 15.561862] usbserial: USB Serial support registered for hp4x
[ 15.567808] usbserial: USB Serial support registered for suunto
[ 15.573901] usbserial: USB Serial support registered for siemens_mpi
[ 15.648832] usbcore: registered new interface driver cdc_mbim
[ 15.667969] usbcore: registered new interface driver ipw
[ 15.673463] usbserial: USB Serial support registered for IPWireless converter
[ 15.696591] usbcore: registered new interface driver option
[ 15.702347] usbserial: USB Serial support registered for GSM modem (1-port)
[ 15.750267] usbcore: registered new interface driver qcserial
[ 15.756205] usbserial: USB Serial support registered for Qualcomm USB modem
[ 15.787067] kmodloader: done loading kernel modules from /etc/modules.d/*
[ 25.961863] option 1-1:1.0: GSM modem (1-port) converter detected
[ 25.968500] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
[ 25.976014] option 1-1:1.1: GSM modem (1-port) converter detected
[ 25.982591] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1
[ 25.990145] option 1-1:1.2: GSM modem (1-port) converter detected
[ 25.996697] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB2
[ 26.004210] option 1-1:1.3: GSM modem (1-port) converter detected
[ 26.010775] usb 1-1: GSM modem (1-port) converter now attached to ttyUSB3
[ 29.128660] br-lan: port 1(eth0.1) entered blocking state
[ 29.134151] br-lan: port 1(eth0.1) entered disabled state
[ 29.140060] device eth0.1 entered promiscuous mode
[ 29.144926] device eth0 entered promiscuous mode
[ 29.186510] br-lan: port 1(eth0.1) entered blocking state
[ 29.192002] br-lan: port 1(eth0.1) entered forwarding state
[ 29.197881] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
[ 30.272029] IPv6: ADDRCONF(NETDEV_CHANGE): br-lan: link becomes ready