I use a Brume2 in Drop-In mode with "some devices". In this case I have to set the DHCP
server on WAN to off. Which will work but does not persist a reboot. After reboot, I can
still see the dhcp.wan.ignore_ori='1' but the dhcp.wan.ignore='1' disappeared. Maybe some
problem in the edge scripts or /lib/function/drip-in-function.sh not taking care about the two
cases "all devices" (where Brume2 DHCP is on and ISP should be off) vs "some devices"
(where Brume2 DHCP should be off and ISP should be on).
When fixing it, I suggest that you don't leave the Brume2 DHCP state "as-is" but switch it
to off in any case, otherwise you provoke problems by having two DHCP servers running.
I did not quite understand the question.
Please refer to this guide to know these two scenarios (methods) of the drop-in gateway:
‘Drop-in Gateway - GL.iNet Router Docs 4
Switching DHCP off on the ISP router is recommended only if you use Drop-In mode with "all devices are networked through drop-in gateway". But I use "Some devices select their own networking gateway" mode, where you still use the ISP router as DHCP server and you manually set static addresses, router, and DNS settings on clients that shall use the Brume2.
Consequently, in this case you should switch off DHCP on the Brume2, which can be done e.g. in Luci by selecting the WAN interface and in DHCP set "ignore this interface" to checked. Which is identical to "uci set dhcp.wan.ignore='1' " on cli. This will work, but the entry will disappear after reboot of the Brume2.
I checked and saw that for drop-in gateways you customized Openwrt with a set of functions, defined in /lib/function/drop-in-function.sh. The functions in this script take care to rename the original settings to dhcp.wan.ignore_ori when switching on drop-in mode and to be able to restore the setting when it is switched off. They are called by /etc/init.d/edgerouter but there it is not distinguished between the two modes of drop-in, so it always assumes DHCP in Brume2 should be switched on. That is a bug from my point of view, because /etc/init.d/edgerouter is called through link in /etc/rc.d/S99edgerouter on boot it will kill my setting of DHCP to off in Brume2.
I see. Now you can just modify /lib/function/drop-in-function.sh so that your changes will not be affected.
I will let developrs to check if they have better solutions.