AC199 EX700 will not work with CM1000 modem

We just switched from DSL to cable using a new Netgear CM1000 modem on Comcast.   The tech came out to connect it and it works fine.  Tried to connect the Netgear AC1900 EX7000 wifi access point and it failed.  The tech was here for 6 hours trying to get it to work.

I guess the question I have is that the AC1900 worked fine with the DSL, but will not with the cable modem.  We started by doing nothing more than connect the modem to the access point and nothing.  If you connect to the AC1900 with a CAT5 wire you can access, but not working on wifi at all.  The settings in the AC1900 all look correct and turned on with no wifi lights on the panel.  Not sure if the cable tech did something, but I can find nothing that would make it act like this.

We tried the Netgear setup a zillion times, making sure to pick access point when setting it up.  

I had another wifi router to try and it works fine.

Could the issue be that the AC1900 EX7000 will not work attached directly to a modem?  It needs a router??