IP changes on port forwarding

[Shrike]

I set up port forwarding, port 80 to 192.168.1.4

Port forwarding works fine.

After a day or so 192.168.1.4 changes to various IPs. such as

8.15.17.117, and 63.251.179.13 both will be listed.

Port forwarding stops working.

I click <resolve now> and it changes back to 192.168.1.4

and starts working again. But will change back after a day.

How can I keep this from happening?

[dslr595148]

#1 What is the exact brand and model of your router?

#2 If you are not on FIOS, what is the brand and model of your modem?