Zyxel DB5401 - trying to add openwrt support

Hi Guys,

my mum's ISP gave her this modem/router which she is not using and she gave to me to play with...

I would like to try to run openwrt on it, my skills are limited but i don't mind playing with some code...
I was just wondering if anyone has already tried anything similar so to jump-start my attempts..

...or if anyone has any recommendation on how to handle zyxel products please feel free to let me know

this is the link to the zyxle prooduct page:

and this is the link to the zip file with manuals/specs from the ISP:

thanks a lot


What SOC does it have? It’s a vdsl modem so that would indicate Broadcom
Do you have serial access?

i am looking around over the internet to find the SOC...for the moment I have not seen anything interesting, i got a 470pages manual... going through...

in the meantime I have opened up the router

i save some pictures here:


I will check better the board to see if i can find any info on the SOC...

regarding serial access, i have a nodemcu which i used as a TTL/USB adapter in the past...for other projects
i can try to use it to get serial access to the router.
I am not really sure how i should connect to the router board, would it be with the 4 gpio pins that i have in my last picture?

thanks a lot


That's where I would start...

i played a bit with it
i set an arduino in reset mode
and connected tx with either 3 of the other pins

i get some garbled things (doesn't seem to matter which pin i use..):

tyT@	@PT@TPUTH}\@!P@j@@@@P\ ]]T'\ P@@D\]!	AQ                                                                                                         @Rկ@A@TQ		*P                                                                                                                                             (BqP	U	@U@Xu  (@@Te
     PUPPP	!                                                                                                                                            qW@H     +@I%@PPU(
@H     (]U@%\UTUT@](T  UU                                                                                                                                  P(Q@
@@UP@(@@U -    Q1MY   ݽU@U	P@@UTA@@Q HP                                                                                                          @PH@}@@AT
(퉕@@	TH(UH}\U(	*5(T                                                                                                                                   ]@@(u(	jTP]@TE@UuQ@PT@TDԿPU
                                 @(@E̩T                                                                                                               @IT@ qD!@*
(@@                                                                                                                                              @(5	@@A@PP@T
PTX    P@u%!Q
 U    %P"  (T)@ PUD

i am probably doing something silly..

any suggestion?


i read on the wiki that the issue was linked to not having a common ground
so i connected arduino's ground to one of the remaining 2 pins and i do get something
still a lot of garbled things but something is readable:

Broadcom, as @jdwl1o1 suspected.

…and to be explicit about, Broadcom implies the death penalty for modem-, phone- and wireless support, rendering any time spent on it wasted (all you'd get, is a wired-only router with rather limited performance (these SOCs depend heavily on proprietary routing acceleration, which is not available either)).

thanks guys,

not the news I hoped for but i understand.

I guess I will just throw it in the bin...

thanks for the support, at least we tried