Good afternoon, I would like to report some problems after updating the TL-WR840n V4 <W>. in the previous firmware version  (0.9.1 3.16 v004c. 1 Build 170912 Rel. 39609n
Hardware: TL-WR840N v4 00000004)
IPV6 was working fine (my internet is PPOE) fiber optics, but in this last update (whose firmware name is TL-WR840Nv4_BR_WISP_0.9.1_3.16_up_boot [180920-rel55953]) IPV6 stopped working, it does not enable at all . I've already formatted it, I've updated the system 3 times and nothing, it's been 2 weeks since I tried to enable ipv6 and nothing works. Detail: I know the username and password of the provider in which I use, other than that, even putting in SLAAC or GET PREFIX, IPV6 does not enable in any way. I believe the error is in the last firmware. I don't want to risk using TFTP because I can't afford to buy another one now. I would like tplink's answer if you can send a firmware more updated than this (link: https: //www.tp-link.com/br/support/download/tl-wr840n-w/v4/) whose name is in this way is TL-WR840N Firmware 180920-rel55953, from brazil. Thank you very much.

Edit: when I try to use the tplink app, when I put admin user and admin password, it's wrong, and on the PC when I put that same login and modem password, it normally accesses.