MT7603EN/MT7612EN Wifi Troubles on Netgear R6220

Here the whole log:

root@OpenWrt:~# dmesg
[    0.000000] Linux version 4.14.95 (buildbot@1fcdec9f6eb0) (gcc version 7.3.0 (OpenWrt GCC 7.3.0 r7676-cddd7b4c77)) #0 SMP Wed Jan 30 12:21:02 2019
[    0.000000] SoC Type: MediaTek MT7621 ver:1 eco:3
[    0.000000] bootconsole [early0] enabled
[    0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc)
[    0.000000] MIPS: machine is Netgear R6220
[    0.000000] Determined physical RAM map:
[    0.000000]  memory: 08000000 @ 00000000 (usable)
[    0.000000] Initrd not found or empty - disabling initrd
[    0.000000] VPE topology {2} total 2
[    0.000000] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.000000] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000000000000-0x0000000007ffffff]
[    0.000000]   HighMem  empty
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000000000-0x0000000007ffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000007ffffff]
[    0.000000] On node 0 totalpages: 32768
[    0.000000] free_area_init_node: node 0, pgdat 80551f80, node_mem_map 81003000
[    0.000000]   Normal zone: 256 pages used for memmap
[    0.000000]   Normal zone: 0 pages reserved
[    0.000000]   Normal zone: 32768 pages, LIFO batch:7
[    0.000000] random: get_random_bytes called from 0x80555740 with crng_init=0
[    0.000000] percpu: Embedded 14 pages/cpu @8110f000 s26256 r8192 d22896 u57344
[    0.000000] pcpu-alloc: s26256 r8192 d22896 u57344 alloc=14*4096
[    0.000000] pcpu-alloc: [0] 0 [0] 1
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 32512
[    0.000000] Kernel command line: console=ttyS0,57600 rootfstype=squashfs,jffs2
[    0.000000] PID hash table entries: 512 (order: -1, 2048 bytes)
[    0.000000] Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
[    0.000000] Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
[    0.000000] Writing ErrCtl register=00020c00
[    0.000000] Readback ErrCtl register=00020c00
[    0.000000] Memory: 123780K/131072K available (4636K kernel code, 239K rwdata, 572K rodata, 236K init, 254K bss, 7292K reserved, 0K cma-reserved, 0K highmem)
[    0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=2, Nodes=1
[    0.000000] Hierarchical RCU implementation.
[    0.000000]  RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
[    0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=2
[    0.000000] NR_IRQS: 256
[    0.000000] clocksource: GIC: mask: 0xffffffffffffffff max_cycles: 0xcaf478abb4, max_idle_ns: 440795247997 ns
[    0.000000] clocksource: MIPS: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 4343773742 ns
[    0.000009] sched_clock: 32 bits at 440MHz, resolution 2ns, wraps every 4880645118ns
[    0.015487] Calibrating delay loop... 586.13 BogoMIPS (lpj=2930688)
[    0.087791] pid_max: default: 32768 minimum: 301
[    0.097087] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.110102] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
[    0.125621] Hierarchical SRCU implementation.
[    0.134859] smp: Bringing up secondary CPUs ...
[    0.156488] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[    0.156496] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[    0.156507] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[    0.156637] CPU1 revision is: 0001992f (MIPS 1004Kc)
[    0.204357] Synchronize counters for CPU 1: done.
[    0.264018] smp: Brought up 1 node, 2 CPUs
[    0.275401] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.294871] futex hash table entries: 512 (order: 2, 16384 bytes)
[    0.307090] pinctrl core: initialized pinctrl subsystem
[    0.318003] NET: Registered protocol family 16
[    0.333323] Can't analyze schedule() prologue at 804829e0
[    0.344010] FPU Affinity set after 11720 emulations
[    0.344716] pull PCIe RST: RALINK_RSTCTRL = 0
[    0.653656] release PCIe RST: RALINK_RSTCTRL = 7000000
[    0.663724] ***** Xtal 40MHz *****
[    0.670452] release PCIe RST: RALINK_RSTCTRL = 7000000
[    0.680660] Port 0 N_FTS = 1b105000
[    0.687556] Port 1 N_FTS = 1b102800
[    0.694480] Port 2 N_FTS = 1b105000
[    1.852910] PCIE1 no card, disable it(RST&CLK)
[    1.861601]  -> 12007f2
[    1.866418] PCIE0 enabled
[    1.871615] PCIE2 enabled
[    1.876800] PCI host bridge /pcie@1e140000 ranges:
[    1.886326]  MEM 0x0000000060000000..0x000000006fffffff
[    1.896683]   IO 0x000000001e160000..0x000000001e16ffff
[    1.907050] PCI coherence region base: 0xbfbf8000, mask/settings: 0x60000000
[    1.932660] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    1.944100] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    1.955326] mt7621_gpio 1e000600.gpio: registering 32 gpios
[    1.967636] PCI host bridge to bus 0000:00
[    1.975659] pci_bus 0000:00: root bus resource [mem 0x60000000-0x6fffffff]
[    1.989314] pci_bus 0000:00: root bus resource [io  0xffffffff]
[    2.001049] pci_bus 0000:00: root bus resource [??? 0x00000000 flags 0x0]
[    2.014534] pci_bus 0000:00: No busn resource found for root bus, will use [bus 00-ff]
[    2.030302] pci 0000:00:00.0: [0e8d:0801] type 01 class 0x060400
[    2.030343] pci 0000:00:00.0: reg 0x10: [mem 0x00000000-0x7fffffff]
[    2.030355] pci 0000:00:00.0: reg 0x14: [mem 0x60300000-0x6030ffff]
[    2.030417] pci 0000:00:00.0: supports D1
[    2.030426] pci 0000:00:00.0: PME# supported from D0 D1 D3hot
[    2.030717] pci 0000:00:01.0: [0e8d:0801] type 01 class 0x060400
[    2.030756] pci 0000:00:01.0: reg 0x10: [mem 0x00000000-0x7fffffff]
[    2.030775] pci 0000:00:01.0: reg 0x14: [mem 0x60310000-0x6031ffff]
[    2.030842] pci 0000:00:01.0: supports D1
[    2.030856] pci 0000:00:01.0: PME# supported from D0 D1 D3hot
[    2.031376] pci 0000:01:00.0: [14c3:7662] type 00 class 0x028000
[    2.031441] pci 0000:01:00.0: reg 0x10: [mem 0x00000000-0x000fffff 64bit]
[    2.031499] pci 0000:01:00.0: reg 0x30: [mem 0x00000000-0x0000ffff pref]
[    2.031598] pci 0000:01:00.0: PME# supported from D0 D3hot D3cold
[    2.031798] pci_bus 0000:01: busn_res: [bus 01-ff] end is updated to 01
[    2.032048] pci 0000:02:00.0: [14c3:7603] type 00 class 0x028000
[    2.032105] pci 0000:02:00.0: reg 0x10: [mem 0x00000000-0x000fffff]
[    2.032249] pci 0000:02:00.0: PME# supported from D0 D3hot D3cold
[    2.032470] pci_bus 0000:02: busn_res: [bus 02-ff] end is updated to 02
[    2.032494] pci_bus 0000:00: busn_res: [bus 00-ff] end is updated to 02
[    2.032569] pci 0000:00:00.0: BAR 0: no space for [mem size 0x80000000]
[    2.045594] pci 0000:00:00.0: BAR 0: failed to assign [mem size 0x80000000]
[    2.059424] pci 0000:00:01.0: BAR 0: no space for [mem size 0x80000000]
[    2.072544] pci 0000:00:01.0: BAR 0: failed to assign [mem size 0x80000000]
[    2.086369] pci 0000:00:00.0: BAR 8: assigned [mem 0x60000000-0x600fffff]
[    2.099853] pci 0000:00:00.0: BAR 9: assigned [mem 0x60100000-0x601fffff pref]
[    2.114194] pci 0000:00:01.0: BAR 8: assigned [mem 0x60200000-0x602fffff]
[    2.127667] pci 0000:00:00.0: BAR 1: assigned [mem 0x60300000-0x6030ffff]
[    2.141152] pci 0000:00:01.0: BAR 1: assigned [mem 0x60310000-0x6031ffff]
[    2.154640] pci 0000:01:00.0: BAR 0: assigned [mem 0x60000000-0x600fffff 64bit]
[    2.169151] pci 0000:01:00.0: BAR 6: assigned [mem 0x60100000-0x6010ffff pref]
[    2.183481] pci 0000:00:00.0: PCI bridge to [bus 01]
[    2.193322] pci 0000:00:00.0:   bridge window [mem 0x60000000-0x600fffff]
[    2.206808] pci 0000:00:00.0:   bridge window [mem 0x60100000-0x601fffff pref]
[    2.221161] pci 0000:02:00.0: BAR 0: assigned [mem 0x60200000-0x602fffff]
[    2.234635] pci 0000:00:01.0: PCI bridge to [bus 02]
[    2.244467] pci 0000:00:01.0:   bridge window [mem 0x60200000-0x602fffff]
[    2.259828] clocksource: Switched to clocksource GIC
[    2.271096] NET: Registered protocol family 2
[    2.280671] TCP established hash table entries: 1024 (order: 0, 4096 bytes)
[    2.294410] TCP bind hash table entries: 1024 (order: 1, 8192 bytes)
[    2.307015] TCP: Hash tables configured (established 1024 bind 1024)
[    2.319736] UDP hash table entries: 256 (order: 1, 8192 bytes)
[    2.331241] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes)
[    2.343866] NET: Registered protocol family 1
[    2.352450] PCI: CLS 0 bytes, default 32
[    2.589770] 4 CPUs re-calibrate udelay(lpj = 2924544)
[    2.600893] Crashlog allocated RAM at address 0x3f00000
[    2.611417] workingset: timestamp_bits=30 max_order=15 bucket_order=0
[    2.632430] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[    2.643931] jffs2: version 2.2 (NAND) (SUMMARY) (LZMA) (RTIME) (CMODE_PRIORITY) (c) 2001-2006 Red Hat, Inc.
[    2.666996] io scheduler noop registered
[    2.674742] io scheduler deadline registered (default)
[    2.685419] gpio-export gpio_export: 1 gpio(s) exported
[    2.696555] Serial: 8250/16550 driver, 16 ports, IRQ sharing enabled
[    2.713016] console [ttyS0] disabled
[    2.720074] 1e000c00.uartlite: ttyS0 at MMIO 0x1e000c00 (irq = 14, base_baud = 3125000) is a 16550A
[    2.737999] console [ttyS0] enabled
[    2.751795] bootconsole [early0] disabled
[    2.769119] cacheinfo: Failed to find cpu0 device node
[    2.779400] cacheinfo: Unable to detect cache hierarchy for CPU 0
[    2.792476] MediaTek Nand driver init, version v2.1 Fix AHB virt2phys error
[    2.806475] Enable NFI Clock
[    2.812224] # MTK NAND # : Use HW ECC
[    2.819515] Device not found, ID: c2f1
[    2.826969] Not Support this Device!
[    2.834429] chip_mode=00000001
[    2.840504] Support this Device in MTK table! c2f1
[    2.850395] [NAND]select ecc bit:4, sparesize :64 spare_per_sector=16
[    2.863260] nand: device found, Manufacturer ID: 0xc2, Chip ID: 0xf1
[    2.875905] nand: Macronix NAND 128MiB 3,3V 8-bit
[    2.885265] nand: 128 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
[    2.900353] Scanning device for bad blocks
[    3.058061] Bad eraseblock 634 at 0x000004f40000
[    3.135983] Bad eraseblock 926 at 0x0000073c0000
[    3.168105] 6 fixed-partitions partitions found on MTD device MT7621-NAND
[    3.181617] Creating 6 MTD partitions on "MT7621-NAND":
[    3.192029] 0x000000000000-0x000000100000 : "u-boot"
[    3.203056] 0x000000100000-0x000000200000 : "SC PID"
[    3.213981] 0x000000200000-0x000000600000 : "kernel"
[    3.224956] 0x000000600000-0x000002200000 : "ubi"
[    3.235558] 0x000002e00000-0x000002f00000 : "factory"
[    3.246680] 0x000004200000-0x000007e00000 : "reserved"
[    3.258445] [mtk_nand] probe successfully!
[    3.267306] Signature matched and data read!
[    3.275805] load_fact_bbt success 1023
[    3.284004] libphy: Fixed MDIO Bus: probed
[    3.362378] libphy: mdio: probed
[    4.768397] mtk_soc_eth 1e100000.ethernet: loaded mt7530 driver
[    4.780928] mtk_soc_eth 1e100000.ethernet eth0: mediatek frame engine at 0xbe100000, irq 16
[    4.800329] NET: Registered protocol family 10
[    4.810562] Segment Routing with IPv6
[    4.817928] NET: Registered protocol family 17
[    4.826896] bridge: filtering via arp/ip/ip6tables is no longer available by default. Update your scripts to load br_netfilter if you need this.
[    4.852689] 8021q: 802.1Q VLAN Support v1.8
[    4.864246] UBI: auto-attach mtd3
[    4.870883] ubi0: attaching mtd3
[    5.134476] ubi0: scanning is finished
[    5.156897] ubi0: attached mtd3 (name "ubi", size 28 MiB)
[    5.167666] ubi0: PEB size: 131072 bytes (128 KiB), LEB size: 126976 bytes
[    5.181355] ubi0: min./max. I/O unit sizes: 2048/2048, sub-page size 2048
[    5.194862] ubi0: VID header offset: 2048 (aligned 2048), data offset: 4096
[    5.208720] ubi0: good PEBs: 224, bad PEBs: 0, corrupted PEBs: 0
[    5.220680] ubi0: user volume: 2, internal volumes: 1, max. volumes count: 128
[    5.234108] mtk_soc_eth 1e100000.ethernet eth0: port 4 link up
[    5.235065] ubi0: max/mean erase counter: 3/1, WL threshold: 4096, image sequence number: 336613720
[    5.264648] ubi0: available PEBs: 0, total reserved PEBs: 224, PEBs reserved for bad PEB handling: 20
[    5.283030] ubi0: background thread "ubi_bgt0d" started, PID 354
[    5.284865] block ubiblock0_0: created from ubi0:0(rootfs)
[    5.305948] ubiblock: device ubiblock0_0 (rootfs) set to be root filesystem
[    5.319825] hctosys: unable to open rtc device (rtc0)
[    5.331717] random: fast init done
[    5.343962] VFS: Mounted root (squashfs filesystem) readonly on device 254:0.
[    5.358757] Freeing unused kernel memory: 236K
[    5.367650] This architecture does not have kernel memory protection.
[    5.709921] mtk_soc_eth 1e100000.ethernet eth0: port 2 link up
[    5.899028] init: Console is alive
[    5.906157] init: - watchdog -
[    6.432158] mtk_soc_eth 1e100000.ethernet eth0: port 3 link up
[    6.486931] kmodloader: loading kernel modules from /etc/modules-boot.d/*
[    6.598981] usbcore: registered new interface driver usbfs
[    6.610071] usbcore: registered new interface driver hub
[    6.620794] usbcore: registered new device driver usb
[    6.639963] xhci-mtk 1e1c0000.xhci: xHCI Host Controller
[    6.650623] xhci-mtk 1e1c0000.xhci: new USB bus registered, assigned bus number 1
[    6.669984] xhci-mtk 1e1c0000.xhci: hcc params 0x01401198 hci version 0x96 quirks 0x0000000000210010
[    6.688362] mtk_soc_eth 1e100000.ethernet eth0: port 1 link up
[    6.688426] xhci-mtk 1e1c0000.xhci: irq 15, io mem 0x1e1c0000
[    6.712448] hub 1-0:1.0: USB hub found
[    6.720224] mtk_soc_eth 1e100000.ethernet eth0: port 0 link up
[    6.731940] hub 1-0:1.0: 2 ports detected
[    6.740623] xhci-mtk 1e1c0000.xhci: xHCI Host Controller
[    6.751259] xhci-mtk 1e1c0000.xhci: new USB bus registered, assigned bus number 2
[    6.766176] xhci-mtk 1e1c0000.xhci: Host supports USB 3.0  SuperSpeed
[    6.779176] usb usb2: We don't know the algorithms for LPM for this host, disabling LPM.
[    6.796196] hub 2-0:1.0: USB hub found
[    6.803769] hub 2-0:1.0: 1 port detected
[    6.814837] kmodloader: done loading kernel modules from /etc/modules-boot.d/*
[    6.840171] init: - preinit -
[    7.062510] mtk_soc_eth 1e100000.ethernet eth0: port 2 link down
[    7.516300] mtk_soc_eth 1e100000.ethernet: PPE started
[    7.613059] random: procd: uninitialized urandom read (4 bytes read)
[    8.780999] mtk_soc_eth 1e100000.ethernet eth0: port 2 link up
[   10.755837] UBIFS (ubi0:1): background thread "ubifs_bgt0_1" started, PID 446
[   10.828815] UBIFS (ubi0:1): recovery needed
[   11.005859] UBIFS (ubi0:1): recovery completed
[   11.014863] UBIFS (ubi0:1): UBIFS: mounted UBI device 0, volume 1, name "rootfs_data"
[   11.030456] UBIFS (ubi0:1): LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[   11.050198] UBIFS (ubi0:1): FS size: 21585920 bytes (20 MiB, 170 LEBs), journal size 1142784 bytes (1 MiB, 9 LEBs)
[   11.070803] UBIFS (ubi0:1): reserved for root: 1019556 bytes (995 KiB)
[   11.083807] UBIFS (ubi0:1): media format: w4/r0 (latest is w5/r0), UUID E8332BE0-8205-4C9C-B059-85F9BD2D430B, small LPT model
[   11.117018] mount_root: switching to ubifs overlay
[   11.159734] urandom-seed: Seeding with /etc/urandom.seed
[   11.327861] mtk_soc_eth 1e100000.ethernet: 0x100 = 0x6060000c, 0x10c = 0x80818
[   11.349755] procd: - early -
[   11.355697] procd: - watchdog -
[   12.049965] procd: - watchdog -
[   12.056520] procd: - ubus -
[   12.122836] random: ubusd: uninitialized urandom read (4 bytes read)
[   12.140826] random: ubusd: uninitialized urandom read (4 bytes read)
[   12.153881] random: ubusd: uninitialized urandom read (4 bytes read)
[   12.167479] procd: - init -
[   12.555555] kmodloader: loading kernel modules from /etc/modules.d/*
[   12.575070] ip6_tables: (C) 2000-2006 Netfilter Core Team
[   12.594755] Loading modules backported from Linux version wt-2017-11-01-0-gfe248fc2c180
[   12.610768] Backport generated by backports.git v4.14-rc2-1-31-g86cf0e5d
[   12.626161] ip_tables: (C) 2000-2006 Netfilter Core Team
[   12.643500] nf_conntrack version 0.5.0 (2048 buckets, 8192 max)
[   12.715237] wireguard: WireGuard 0.0.20190123 loaded. See www.wireguard.com for information.
[   12.732094] wireguard: Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
[   12.762137] xt_time: kernel timezone is -0000
[   12.814063] bus=0x2, slot = 0x1, irq=0xff
[   12.822316] mt7603e 0000:02:00.0: ASIC revision: 76030010
[   13.861048] mt7603e 0000:02:00.0: Firmware Version: ap_pcie
[   13.872257] mt7603e 0000:02:00.0: Build Time: 20160107100755
[   13.919827] mt7603e 0000:02:00.0: firmware init done
[   14.095190] ieee80211 phy0: Selected rate control algorithm 'minstrel_ht'
[   14.112433] bus=0x1, slot = 0x0, irq=0xff
[   14.120743] mt76x2e 0000:01:00.0: ASIC revision: 76120044
[   14.842840] mt76x2e 0000:01:00.0: ROM patch build: 20141115060606a
[   14.858663] mt76x2e 0000:01:00.0: Firmware Version: 0.0.00
[   14.869647] mt76x2e 0000:01:00.0: Build: 1
[   14.877798] mt76x2e 0000:01:00.0: Build Time: 201507311614____
[   14.909827] mt76x2e 0000:01:00.0: Firmware running!
[   14.920953] ieee80211 phy1: Selected rate control algorithm 'minstrel_ht'
[   14.930827] PPP generic driver version 2.4.2
[   14.941052] NET: Registered protocol family 24
[   14.953485] kmodloader: done loading kernel modules from /etc/modules.d/*
[   15.579177] urandom_read: 5 callbacks suppressed
[   15.579189] random: jshn: uninitialized urandom read (4 bytes read)
[   22.255142] mtk_soc_eth 1e100000.ethernet: PPE started
[   22.274392] device eth0 entered promiscuous mode
[   22.289608] br-lan: port 1(eth0.1) entered blocking state
[   22.300719] br-lan: port 1(eth0.1) entered disabled state
[   22.311996] device eth0.1 entered promiscuous mode
[   22.329478] br-lan: port 1(eth0.1) entered blocking state
[   22.340290] br-lan: port 1(eth0.1) entered forwarding state
[   22.351850] IPv6: ADDRCONF(NETDEV_UP): br-lan: link is not ready
[   23.340236] IPv6: ADDRCONF(NETDEV_CHANGE): br-lan: link becomes ready
[   25.510251] IPv6: ADDRCONF(NETDEV_UP): wlan0-1: link is not ready
[   25.958162] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready
[   25.970561] br-lan: port 2(wlan0-1) entered blocking state
[   25.981626] br-lan: port 2(wlan0-1) entered disabled state
[   25.993137] device wlan0-1 entered promiscuous mode
[   26.025329] br-lan: port 3(wlan1) entered blocking state
[   26.036080] br-lan: port 3(wlan1) entered disabled state
[   26.047452] device wlan1 entered promiscuous mode
[   26.057299] br-lan: port 3(wlan1) entered blocking state
[   26.068004] br-lan: port 3(wlan1) entered forwarding state
[   26.560083] br-lan: port 3(wlan1) entered disabled state
[   27.415180] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready
[   27.828251] IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
[   27.841324] br-lan: port 3(wlan1) entered blocking state
[   27.851990] br-lan: port 3(wlan1) entered forwarding state
[   29.771831] wlan0: authenticate with 40:4e:36:85:12:7b
[   29.787474] wlan0: send auth to 40:4e:36:85:12:7b (try 1/3)
[   29.801881] wlan0: authenticated
[   29.809923] wlan0: associate with 40:4e:36:85:12:7b (try 1/3)
[   29.833332] wlan0: RX AssocResp from 40:4e:36:85:12:7b (capab=0x1431 status=0 aid=3)
[   29.848969] wlan0: associated
[   29.874815] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   30.323437] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0-1: link becomes ready
[   30.336870] br-lan: port 2(wlan0-1) entered blocking state
[   30.347935] br-lan: port 2(wlan0-1) entered forwarding state
[   46.518761] random: crng init done

I'm no longer using USB for tethering but the router keeps rebooting for no raison. There is definitely something wrong with bad blocks.
Should I install one of the precompiled images ?

True, you have 2 bad eraseblocks:

But both eraseblocks are quite far back in the flash and lay squarely in the "reserved" partition where they don't do any harm. Most importantly, they are not in front of 0x2e00000 where they would shift where OpenWrt looks for the "factory" partition. So no, those precompiled images with different offsets will do you no good, at best they won't make any difference.

You could try a snapshot build, I seem to remember they are quite a bit further developed than 18.06. But there's always the possibility of a different hardware failure (sometimes as trivial as a wonky power supply.)

Edit, for clarity: mine has been running snapshot from the get-go, I actually don't know how much worse 18.06 behaves. it has been rock stable on r9901 for about two months now.

Thanks @takimata for your answer. I will consider using an other power adapter.
If it doesn't help, I'll try for a snapshot image.

using the release of openwrt 19.07.0 i can confirm that my MAC address is the same after reboot (comment 56). So the "bad eraseblock" on my R6220 doesn't shift the reading of the partition anymore. Thank you for all your help. Thanks a lot to all contributors and Jo-Philipp Wich