[acunico]

Finally, good news I like to share with you as for suggestions you provided.

Router works well, simply it's a black box and it's not possible to change configuration (as for example in case of change of main router)

Not forgetting reset button does not work on Buffalo WZR-1166DHP, I was looking to get back access to Router Admin Page (now I know that was not possible since I applied Repeater Mode) or at least to serial console as already done in the past.

I skip about serial and multimeter as they are in previous messages

I went back to the beginning, reading again Client Bridge e Repeater Bridge configuration and why I applied Repeater Bridge more than roughly three years ago.

Finally, I see a kind of light in the tunnel when I read
New to Client Bridging?
Here's some extra information about client bridging and some, perhaps unexpected, side effects ........................................
When you've switched to Client Bridge mode you won't be accessing the remote AP until your IP changes unless your box and the remote network are on the same subnet.
here
https://wiki.dd-wrt.com/wiki/index.php/Wireless_Bridge

So I wired connected main router (192.168.10011) to secondary router (192.168.200.1) port 1 (just left to wan port), booted my Linux partition, added one fixed ip address to to wired eth accordingly to network address I set to secondary router, then I browsed secondary router address (192.168.200.1) and I was in!!
Useless to say I put down notes and saved all screens of admin pages.
Thanks again for your appreciated support
Alessandro

[kernel-panic69]

Glad you got it sorted, marking this as solved.