Cox gigablast and AirPort Extreme 802.11ac

I can't connect via wireless, it connects to the airport, but says there is no internet, at this point I can't even connect to the modems homepage (192.168.100.1)

You should not be connecting to the modem homepage ever. You should be able to reach the Extreme only.

If it works by cable, as per this,

I can connect it as modem -> airport extreme -> computer via cable and it's fine.

Then there is a good chance there is something simple gone wrong.

Check your Network in the computer running by cable. Look carefully at the IP setup plus Router and DNS values. I am showing the wireless values.. but same thing.. you need to work through both.

Then on the computer that is failing to work by wireless, open the network advanced and check all the values.

If the Router and DNS values do not match, try manually setting them.

There is a good chance things are working on ethernet via IPv6 and failing because of some limitation with IPv4 on your other devices especially older products.

Always good to ensure your old settings are removed. Wireless is always more of a problem. Just like you reset the Airport Extreme, reset the wireless in your computer or devices.. this means deleting all the old wireless names you have stored.

Make sure the wireless name in the Airport Extreme is SHORT, <8 characters, No SPACES, and pure alphanumerics.

Passwords same rules but 8-20 characters.

Reboot the client devices and rediscover the wireless. Make sure you are getting correct router and DNS settings.

Post screenshots if you need more help. Particularly screen shot of the ethernet working and the wireless not working.

We need to see all the details so please just cover up IPv6 values as per my screenshot. The rest is not info that anyone can use.

In the end.. I actually agree with Bob.. it is really time for a new router.. especially with that speed internet.. the Airport is just not good enough.

First thing that you should be aware of, and that is that the AirPort Extreme......if it can be made to work....will only deliver about one third the speed of your Gigabit Internet connection, from the modem, so I'm not sure how much time that you want to spend trying to get the AirPort Extreme to work with your new Internet connection.

If you do want to try to get the AirPort Extreme working, it will first need to be reset back to its factory default settings and then set up again, so that it might be able to pick up the new correct settings that it needs. No guarantees that this will work though, so it is your call as to whether you want to spend more time on this.

If you have performed a factory default reset, then sequence is the next most important thing after that.

Please try the following:

Disconnect the Ethernet cable from the AirPort Extreme

Power off the modem completely by pulling the power supply cord or pulling the cord from the wall AC socket

Leave the modem off for at least 30 minutes. 60 would be better as it sometimes takes the equipment back at the cable company some time to completely reset and issue a new fresh connection.

During the time the modem is powered off, perform another factory default reset on the AirPort Extreme again.

Power off the AirPort Extreme

After the modem has been powered off for at least 30 minutes.....60 would be better, connect the Ethernet cable from the modem to the WAN "O" port on the AirPort Extreme

Power up the modem and let it run by itself for at least 5 minutes

Power up the AirPort Extreme and let it run a few minutes

Try the setup again

If things are reasonably successful, the IPv6 settings on the AirPort will still need to be changed manually

Post back when you are at this point.