It has gone from bad to worse. I decided to make changes in small batches, save and reboot.

Made the first change, adding the DHCP pool, saved and rebooted. Now when it comes up I can't contact it, either via its "real" IP address or via its 192.168.1.254 address (with static addresses set on the laptop). I can't reach it via Ethernet or wifi (even though I get a link light for both).

From my experience so far I really couldn't recommend this to anyone who needs to actually make use of even the basic features beyond just a "standard" NAT setup.

I guess I'll have to do some sort of factory reset now to get it back.