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I don't think that this is a stupid question, and I would love to help you with this. You can make these changes in the file etc/hostapd/udhcpd-for-hostapd.conf, in the first lines you will see the range (start and end) that you can change. And on the last section of the file (# Currently supported options, for more info, see options.c), you can change the subnet on the line opt subnet 255.255.255.0.
I hope you find this information useful.
Have a nice day.
It is good to know that it worked. About changing the IP Address, you can do this with command: ifconfig wlan0 192.168.138.1 netmask 255.255.255.0 (Changing it to the right IP Address that you want), but you have to do this every time that you reboot your Edison . To do it automatically you can create a script and a service, for example:
ifconfig wlan0 192.168.138.1 netmask 255.255.255.0
Description=Sets static ip on boot
I hope you find this helpful.
Have a nice weekend.