Hi Sudinna.
If you have access to the console eBox, log in as root and execute:
#ifconfig
This is a list of your interfaces, for example, you are going to see something like:
eth0 192.168.1.1 ....
eth1 192.168.20.200 ...
eth3 10.0.0.1 ...
Once identified the interface in conflict, change the IP with:
#ifconfig eth1 192.168.20.200 netmask 255.255.255.0
And try access to web enviroment again.
Regards!