Like Ecnerwal already said, this is not going to work. (with just the NVG510 alone)
The problem here is that you're getting a public ip from your modem. This means the modem itself does not act as a DHCP-server. The other method you linked to only works if there is another DHCP-server.
Normally the router/access-point (NVG510) would get an ip from the modem via its WAN-port after which you could use its internal DHCP-server to issue private ip ranges on the LAN-side.
But because this WAN-port is a DSL-port and does not work (correctly) as a normal WAN-port you can't use it. So you would need to connect the modem to a LAN-port and that port should get the public ip. But thats not possible because all the LAN-ports should get the same ip-range to be able to communicate with each other.
There are 3 possible solutions to this:
- You could use a computer to directly connect to the modem and share the internet via a second network-adapter. You can connect your NVG510 to that because your computer acts as a DHCP-server. Downside is that your computer always needs to be on.
- You could get your hands on a cheap broadband router which only acts as DHCP-server (no WiFi necessary because you could connect your NVG510 to it)
- You could buy a less-cheaper broadband router which also has wireless capabilities.
Comcast Xfinity, like all ISPs that are also cable TV providers, uses DOCSIS. Most likely version 3.0.
DOCSIS defines both layer 1 and 2. It defines the physical layer as RF signals between 5MHz and 1GHz over 75ohm coaxial cable at certain power levels, and channelized into 6MHz channels (for North America and other NTSC/ATSC TV markets) or 8MHz channels (EuroDOCSIS, for PAL TV markets) just like local TV channels, so it can use unused TV channel frequencies on the cable TV cable so it doesn't interfere with your cable TV reception. It also defines the link layer but that's a bit more complicated to describe here.
DOCSIS stands for "Data Over Cable System Interface Specification", and was developed by CableLabs, a consortium of the cable TV industry. I believe the DOCSIS standards are freely downloadable from CableLabs, and fairly readable as technical standards go (which isn't saying much).
Verizon FiOS started as BPON but is transitioning to GPON ([Broadband|Gigabit] Passive Optical Network). The BPON standard is ITU-T G.983. GPON is ITU-T G.984. These PON standards also specify both layers 1 and 2.
If you get your broadband Internet service from a landline telephone company that hasn't gone to BPON/GPON yet, then it is probably some flavor of DSL (Digital Subscriber Line), most likely ADSL2+ or VDSL2 nowadays. Again, the *DSL standards specify both the physical and data link layers.
Note that I'm really saying what protocol your broadband modem or fiber ONT speaks to the ISP. If your router does not have an integrated modem or ONT, then it uses its Ethernet WAN port to speak to the standalone modem or ONT.
Best Answer
The answer is no. In order to use it as a router the device has to have an "incoming" ethernet port. This is where you would plug the Ethernet cable from the Comcast modem and that interface would be assigned the public IP.
Since there is no photo of the back I am going to use my own device that looks similar and it has no ethernet port - it is because the modem and router are connected internally thus there is no need for it.