Setting up NAS for Web Host

I have a Synology NAS, DS223 that I’m using to backup my photography images. I’d like to also use it to host my business Web site, and perhaps additional sites for other interests. I have installed Apache, php, and Web Station.

I was watching the video on how to setup “Web-hosting on Synology.” My setup appeared to be fine until I got to the “Router Configuration” section. When I go to External Access > Router Configuration, I get an error “Your gateway setting is invalid.” If I go to the Network Settings, I don’t know what to look for there that might need changing.

Can you help me see what I need to change? I have attached screen shots that show my setup thus far.

Here’s the other screenshot of my Network Interface screen: