LTE not working with TL-MR6400 v5.3

Installing and Using OpenWrt
1

I have installed openwrt to TL-MR6400 v5.3 with these instructions:

The installation goes ok but I can't access internet behind the WWAN from a LAN attached PC. The wwan gets ip address from ISP and shows it on the interface list as in the attached screenshot.
image
I have tried deleting the WAN and WAN6 interfaces but that does not help.
LTEWAN is added to the firewall wan zone.
I have a prepaid SIM card which doesn't get public ip address.
Could this be the reason to the problem?
Or is there something different in the V5.3 device?
I also tried with version 22.03.3 of openwrt (see below) but it has same issue.
What could be wrong?
Thanks for any help!

System

Hostname OpenWrt
Model TP-Link TL-MR6400 v5
Architecture MediaTek MT7628AN ver:1 eco:2
Target Platform ramips/mt76x8
Firmware Version OpenWrt 22.03.3 r20028-43d71ad93e / LuCI openwrt-22.03 branch git-22.361.69894-438c598
2

Can you access internet from the router itself?
Please show the output of the following commands (from the router):

ping 8.8.8.8
ip r
ip l
3

No, this is what happens

| |.-----.-----.-----.| | | |.----.| |_
| - || _ | -| || | | || || |
|_____|| |||||___||| |____|
|| W I R E L E S S F R E E D O M

OpenWrt 22.03.3, r20028-43d71ad93e

root@OpenWrt:~# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
^C
--- 8.8.8.8 ping statistics ---
12 packets transmitted, 0 packets received, 100% packet loss
root@OpenWrt:~# ip r
default via 10.64.219.254 dev wwan0
10.64.219.252/30 dev wwan0 scope link src 10.64.219.253
192.168.1.0/24 dev br-lan scope link src 192.168.1.1
root@OpenWrt:~# ip l
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP qlen 1000
link/ether 9c:a2:f4:57:ae:50 brd ff:ff:ff:ff:ff:ff
4: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
link/ether 9c:a2:f4:57:ae:50 brd ff:ff:ff:ff:ff:ff
5: wwan0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UNKNOWN qlen 1000
link/[65534]
6: br-lan: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
link/ether 9c:a2:f4:57:ae:50 brd ff:ff:ff:ff:ff:ff
7: eth0.1@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-lan state UP qlen 1000
link/ether 9c:a2:f4:57:ae:50 brd ff:ff:ff:ff:ff:ff
8: eth0.2@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000
link/ether 9c:a2:f4:57:ae:50 brd ff:ff:ff:ff:ff:ff
root@OpenWrt:~#

4

Please run 2 more:
cat /sys/class/net/wwan0/qmi/raw_ip
and
cat /sys/kernel/debug/usb/devices

Please use forum formatting when posting command output - look for </> icon.

5 

root@OpenWrt:~# cat /sys/class/net/wwan0/qmi/raw_ip
Y
root@OpenWrt:~#
root@OpenWrt:~# cat /sys/kernel/debug/usb/devices

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480  MxCh= 1
B:  Alloc=  0/800 us ( 0%), #Int=  0, #Iso=  0
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev= 5.10
S:  Manufacturer=Linux 5.10.161 ehci_hcd
S:  Product=EHCI Host Controller
S:  SerialNumber=101c0000.ehci
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   4 Ivl=256ms

T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=480  MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=05c6 ProdID=9025 Rev= 3.18
S:  Manufacturer=Android
S:  Product=Android
S:  SerialNumber=91ec92ba
C:* #Ifs= 9 Cfg#= 1 Atr=a0 MxPwr=500mA
A:  FirstIf#= 6 IfCount= 3 Cls=01(audio) Sub=00 Prot=00
I:* If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 1 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none)
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=84(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none)
E:  Ad=86(I) Atr=03(Int.) MxPS=  10 Ivl=32ms
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=qmi_wwan
E:  Ad=88(I) Atr=03(Int.) MxPS=   8 Ivl=32ms
E:  Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 5 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=(none)
E:  Ad=89(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=125us
I:* If#= 6 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=(none)
I:* If#= 7 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=(none)
I:  If#= 7 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=(none)
E:  Ad=8a(I) Atr=05(Isoc) MxPS=  16 Ivl=1ms
I:* If#= 8 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=(none)
I:  If#= 8 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=(none)
E:  Ad=07(O) Atr=09(Isoc) MxPS=  16 Ivl=1ms

T:  Bus=02 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12   MxCh= 1
B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
D:  Ver= 1.10 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0001 Rev= 5.10
S:  Manufacturer=Linux 5.10.161 ohci_hcd
S:  Product=Generic Platform OHCI controller
S:  SerialNumber=101c1000.ohci
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   2 Ivl=255ms
6

All looks good. Please install tcpdump package then open another connection to the router and run
tcpdump -vv -i wwan0
Then from the other connection run ping 8.8.8.8 for a few seconds, then stop tcpdump with Ctrl-C and post its output.