Via cable, the upgrade completed without error, the modem restarded and I can login on interface with "BETA" written on the background of the page BUT
-) I can't connect to the IPS anymore (blank page during wizard configuration)
-) I can't upgrade other firmare (I can select the file but clicking on the upgrade button the page give connection lost error)
-) I can't reset the router (internal error on the page and the button on back does nothing)
Other functions of the mgnt page work (for example wireless configuration, security, etc)

You may do a hard reset by pressing the reset button for 10 seconds. If problem persists, you may contact tplink tech support to get help.

**WARNING** - Do not install the patched firmware using the link provided by support http://static.tp-link.com/MR6400_voip_beta_2016-09-06_15.01.35_1474602142560j.zip.

This firmware will essentially brick your MR6400 V1. I have unfortunately confirmed this and am awaiting a response from support on the matter. The router will still work as a network router but is unstable, 3G/4G functionality is gone and the ability to flash back to the latest update no longer works and keeps failing with "Connection was reset" each time you attempt to upload the firmware from the firmware upgrade screen.

Anyway hope this warning helps someone. I will update with more once support responds. Quite disappointed by all of this to be honest.

I solved the problem with TL-MR6400(EU)_V2_170912

http://www.tp-link.es/download/TL-MR6400.html#Firmware



TL-MR6400(EU)_V2_170912









Fixed the bug that IPSec VPN data cannot be passed.








[TD]Bug Fixed:1. Fixed the bug that slaac cannot connect to IPv6 network in EWAN mode.2.3. Fixed the bug that device may fail to dial up if the ISP has more than one network type.

Fecha de Publicación: 2017-09-12	Idioma: English	Tamaño de Archivo: 21.29 MB
[TABLE="width: 924"] [TR]	Modifications and Bug Fixes
Notes	For TL-MR6400(EU)_V2.0.

[/TD]
[/TR]
[/TABLE]

pedrobotin wrote

I solved the problem with TL-MR6400(EU)_V2_170912

http://www.tp-link.es/download/TL-MR6400.html#Firmware













Fixed the bug that IPSec VPN data cannot be passed.







[TD]Bug Fixed:1. Fixed the bug that slaac cannot connect to IPv6 network in EWAN mode.2.3. Fixed the bug that device may fail to dial up if the ISP has more than one network type.

Fecha de Publicación: 2017-09-12	Idioma: English	Tamaño de Archivo: 21.29 MB
[TABLE="width: 924"] [TR]	Modifications and Bug Fixes
Notes	For TL-MR6400(EU)_V2.0.

[/TD]
[/TR]
[/TABLE]

did you install it on v1 versions? (1.0.12 Build 160322 Rel.33912n)
have you already had v2 versions?

did you install it on the v1 version?
have you already had v2 versions?

I wrote to support(support@tp-link.com) and they sent me the firmware MR6400_voip_beta_2016-09-06_15.01.35
I installed it after restoring the Factory Defaults and everything works:VPN and VOIP
:cool: