I have the same problem.  My ANOVA paired beautifully until I switched my modem just this week.  I tried everything including partitioning the 2.4 and5 gh bandwidths, except temporarily deactivating the 5gh, as waiting for anova tech support to get back before taking this annoying step. I just don't know what deactivating would do to the other devices in my house, as this has already cost a lot of time and downstream effects.  I wish I had never upgraded as suggested by xfinity.  Next time, I wait until 3rd parties have a chance to catch up. I  would appreciate others' ideas as well. here is what i found on line that appears from xfinity site.  I have spent hours trying to figure this out.  

Additional Steps to Connect Some Third-Party Devices to Your WiFi Network

AMCREST CAMERA, ANOVA PRECISION COOKER, LIFX BULBS, IROBOT VACUUM AND ZMODO CAMERA

If you can't set up your Amcrest Camera, Anova Precision Cooker, iRobot Vacuum, LIFX Bulbs and/or Zmodo camera with the device’s mobile app, you will need to temporarily disable the 5 GHz WiFi band and complete the setup using the 2.4 GHz band. To do this, follow the steps below.

1. From a computer or device connected to the Gateway, open an Internet browser and access the Admin Tool at http://10.0.0.1.
2. Once logged in, select Connection and then Wi-Fi.
3. Select EDIT at the end of the row for the 5 GHz Frequency Band.
4. Select Disable and then SAVE SETTINGS.
5. Complete set up of the device using the device’s app.
6. Go back into the Admin Tool and re-enable the 5 GHz band.