|servers/network equipment never use dhcp but are statically assigned ip addresses. Usually you take a subnet like 192.168.1.x and carve it up to those ips statically assigned and those for dhcp and those you hold in reserve. It would look something like this;|
192.168.1.1-25 static assignments
192.168.1.26-200 dhcp scope
192.168.1.201-254 reserved for growth
Your lan should not be in the public ip range for security reasons.
You need to get a network person in. With a different public ip you would need to
change dns server ips
change dns server forwarders
properly configure the web page
properly configure the lan and wan settings
properly forward in the internet router to your web page
And there could be more depending on how you are physically setup...