How to set different IP class in "IP address: and "Default router" and save it

[Ant3ng]

About IPv4 Address Configuration, I want to make IP address static.

I want to set up as follows

IP address (camera itself) : 192.168.0.40
Subnet mask: 255.255.255.0
Default router: 192.168.100.1

Issue is when I do above one, system says "Incorrect default router value. Must be in the same IP class as the IP address value."
I know what this error says. But I need to do it for some reason.
And there is no description about how to do it in manual.

How can I set up above configuration??

[Ant3ng]

I solved the problem myself

Go to System Options
-> Advanced
-> Plain Config
-> Network

In plain config, there is no error message if I set up above configuration.