AE Flashing Amber (Status: Internet Connection) but Internet Green

Question

Apologies if this has been asked before, I couldn't find an answer.
I'm on an AE with a Motorola SB6120 modem, paying for Comcast service.
My AE worked fine two weeks ago when I was on Centurylink at another address.
Problem:
AE is flashing Amber.
Status says "Internet Connection", yet...
AirPort Utility tells me that Internet is Green. Plus, I'm typing this through my wifi/internet, so it appears I'm online.
The other major issue is that none of my other wifi-capable devices can connect to my network. Only my MacBook. Not my iPhone, nor my wife's Dell laptop or Droid phone, nor my Nest thermostat. All can see the network, but none can connect to it. They either time out or, in the case of the Dell, say they can't find an IP address.
I have factory reset the AE, unplugged and re-plugged everything in every order I can think of. I've shut down my computer a half dozen times.
When I factory reset the AE, it was green/green for a moment, then went back to flashing Amber. At that point, it had two "Status" issues: Internet Connection and DNS Servers. I entered the DNS default: 75.75.75.75 and 75.75.76.76. DNS "status" went away, but "internet connection" remains.
When I click on the AE icon on the AirPort Utility, it gives the network name I chose, IP address is blank, the serial number is there and the version is 7.6.1. It lists one wireless client.
If I drill deeper, the "internet" menu says I'm connected using DHCP. IPv4 Address is blank. Subnet Mask is 255.255.255.0 and Router address is 192.168.100.1. I gave the DNS servers above, and IPv6 servers and domain name are blank.  On the wireless menu, the network mode is "create a wireless network", the network name is correct, it's WPA2 Personal security. On the "Network" menu, the Router Mode is "Off (Bridge Mode). All else is greyed out.
If anyone can help, it would be greatly, greatly appreciated. I am at wits end, my wife cannot connect to our home network, and I am questioning why I bought an AE when every other router seems to work better.
Many thanks.

Answer 1

Vagabond0079 wrote:
I entered the DNS default: 75.75.75.75 and 75.75.76.76. DNS "status" went away, but "internet connection" remains.
Not sure what you mean by default, as those are Google DNS addresses. The default would be to not enter anything and allow Comcast to provide them. In a perfect world Comcast would provide you with the fastest, most reliable DNS service, but that is often not the case, which is why there is OpenDNS, Google Public DNS, etc. In any case, that's not your current problem and now that you have that part working you can decide if that's what you need later.
On the "Network" menu, the Router Mode is "Off (Bridge Mode). All else is greyed out.
There's the problem. It should be "Share a public IP address". Bridge Mode just short circuits the router, which is why only one device is connecting.