I faintly remember doing that with instructions on the wiki before but couldnt find them this time around.
Which one of them?
What is your goal here? Is the OpenWrt device intended to be a dumb AP/wifi extender, or are you trying to setup a different network behind the OpenWrt router?
the admin page of the router im connected to(lets call it X) with the openwrt router(Y). Ive already set the subnet of Y to different one than the X. There was one last step to do so i can see the admin page of X while being connected to Y and thats what i cant figure out.
my openwrt router (Y) is connected to another router(X) thats connected to internet, and thats how devices connected to Y get online. I have already did the steps relating to this, there was one last step to do so i can see the admin page of X while being connected to Y and thats what i cant figure out.
your each router has an IP address itself.
e.g:
X - 192.168.1.1 admin page at 192.168.1.1
Y - 192.168.2.1 admin page at 192.168.2.1
if your PC connected to Y, you can access X at 192.168.1.1, same.
you should be able to see both admins pages from a device closer to the clients ...
Yes, but i cant connect to X admin page at 192.168.1.1 (certain the address is correct) unfortunately. I remember there was an extra step where i had to set up an interface so i can connect to X subnet from Y. Maybe a static address interface? Really cant remember.
sure, I mean Y is connected to/from X.
I can do this in my home always, no special settings needed.
that statement doesn't make any sense, since it work both ways ...
lets do a reboot ...
do you need/want double NAT ? if not, the openwrt router could be set up as a dumb AP ?
My first router 192.168.1.1 (static), and ---DHCP--- to my second router 192.168.2.1 (static also).
If my PC connected to second router, I still can access 192.168.1.1. no special settings, all openwrt defaults.
(from 1st, the 2nd got an IP 192.168.1.xxx, my PC got 192.168.2.xxx)
I do not know where the NAT is. is it a double NAT?
This tells us how the 2 routers are connected, but if does not tell us why you installed router y. What is the purpose of router y in your network?
Confusing as to how the wifi connected device serves a named puropose here.
Perhaps a sketch or diagram will assist my / our understanding
@RadioOperator 
...to the Tower .... Debbie's comin' in for a landing.
sry could'nt help.. it's in my head now...
I learnt alot from that network diag. topic.
Here is simple, 1st+2nd+PC in serial and PC opens the admin page of 1st.
opens, or wants to open ?
I did not get problems on this, just tested, still ok.
as it should be, unless specifically blocked....
Yes, I never touch the Firewall / routings settings, every time I try to mod on it, something would be wrong.
Too many things I'm not sure. This is the openwrt con's comparing to stock fw.
The openwrt settings is too complex for normal users, not easy to do right, once a little bit wrong, maybe need factory reset and redo.
You never answered this. Why does router y exist in your network??