Wireless Bridge on Netgear WNDR3800

Hi All,
I'm a novice to OpenWRT. I want to convert my router from DD-WRT to OpenWRT.

I'm trying to get a bridge working on my Netgear WNDR3800.
I followed all steps in this guide https://openwrt.org/docs/guide-user/network/wifi/atheroswds
I use "save" to get all options in place for the LAN port, set up the wireless section , use "save and apply" . I get a scene saying it is reverting back to previous settings.
When I use the option to apply anyway I can't connect to the router anymore.

If I only setup the LAN settings to fixed and no DHCP, as in the guide above, I'm also unable to connect to the router (yes, the ethernet port has a fixed IP in the range of the router).

What am I doing wrong?

Using an ancient guide... find something newer... having two network ranges statically assigned to your "management pc" and corresponding router subinterfaces ( optionally ports ) will make your life alot easier... read browser errors carefully and try alternate browsers / private tabs / cache flushing...