My home network uses a nest of linux boxen, one of which has multiple interfaces, and acts as my firewall/bastion/router to the big-I internet. Behind that firewall, I have a wired subnet and several wireless subnets. My wired internal network is 192.168.3.0/24. There are several old wrt-54 boxes serving as wireless routers for the wireless nets. Each of their WAN interfaces plugs into the wired net, and they run their own DHCP servers for their wireless segments, eg one of them will have a WAN address at 192.168.3.20, and LAN addresses at 192.168.20.0/24.
I'm replacing one of those old wrt-54s with the R7800, and want to use it the same way; WAN plugged into my wired internal network, supporting its own wireless subnet.
I'm guessing that this newer box likely isn't going to let me admin it by plugging in the WAN port, I'll need to plug into a LAN port. Right track?
I actually had already read those two pages, and a bunch more. The key bit that I was missing was that I needed to not use the WAN port, but one of the LAN ports instead.
My I suggest a tweak to the doc? In https://openwrt.org/docs/guide-quick-start/factory_installation ? Perhaps under "Flash the firmware", s/Connect to the device via Ethernet cable/Connect to the device via Ethernet cable using one of the LAN ports/. Had I seen that when I started, it would have saved me some time, and y'all a newbie question.