TL-MR6400 V54: Major firmware issue with 4G backup mode

TL-MR6400 V54: Major firmware issue with 4G backup mode
TL-MR6400 V54: Major firmware issue with 4G backup mode
2020-12-31 15:50:13
Model: TL-MR6400
Hardware Version: V5
Firmware Version: 200511

Hi together,


we've got a brand new MR6400 4G router. It is operated as "wireless repeater" with primary WAN internet and 3G/4G backup option enabled.



- Wireless repeater mode

- Dynamic IP via WAN

- 3G/4G backup option enabled


Once running, the device does it's job quite good (switchover from failed WAN Internet to LTE within seconds!).


Problem: Initial startup upon reboot / after power loss results always in "no Internet connection - contact your ISP" - no automatic fallback to mobile network happens!

-> as reported, no internet is available in the network of the MR6400
-> the device seems not to recognize the "internet" at the WAN port ("contact your ISP"). Every other device connected the same way to WAN gets working internet

-> in the overview page, the WAN DHCP lease data is displayed correctly

-> the LED "internet connection established" on the device is on(!)

-> despite of the WAN connection problem, the device does NOT switch over to the 3G/4G backup - it just stays in disconnected state (!)

Result: If you reboot the device or just have a power-loss, you will end up with no internet connection!



- Firmware: Just edit the WAN settings in the MR6400 (e.g. configure static ip instead of dynamic ip, or the other way around, it doesn't matter - just cause a "WAN settings changed" event) which the device seems to do an internal restart of the WAN port. This brings the internet connection back online immediately.

- Hardware: Unplug the WAN port and replug it (which should also cause a restart of the WAN interface in the device) - internet link is then successfully established

The fail-over to 3G/4G works after one of those procedures automatically and within seconds, as it should be.


As far as I can tell, with the circumstances described, this smells like a major firmware bug to me. If I should make a wild guess there are two different bugs:

1) the bootup-sequence in "wireless router mode" seems to be erroneous and results in a faulty configured WAN-connection. The "internet link" shows also a false "link established" state.

2) after bootup the device fails to enable the automatic "3G/4G backup" (which is one of the major tasks it was purchased for...)

Observation: After an internal soft-restart of the WAN-interface everything works fine.


Any suggestions? The device is quite nice, I would really appreciate if this could be solved by a firmware update in the near future :-)


Best wishes and a happy new year,