So, I have correctly installed an AC1750 C7, and am using it as an extender.  The DHCP is disabled.

It's looped from an AC1200, which is also used as an extender. DHCP is also disabled.

The lights on the AC1200 are steady.  No flashing.

All the lights, except the power LED, are flashing on the C7.  The two wifi lights, the light right next to the power light, and the connection from the AC1200 (though, this connection is not flashing as much as the others).

However, everything is working.  I have wireless and the signal is strong.  I checked all the settings for login, wifi security, LAN (DHCP is disabled), network name, etc.  I gave the two routers different IP addresses.  Don't know if it makes a difference, but the 1200 is less than 200, the C7 is slighly greater than 200.

I don't care if the lights are flashing, since everything is working, but I'm more curious as to why it's happening.

Thanks.