Office Move - New Modem with WiFi - Have SonicWall Router

Landscape:

* moved to new office space

* Comcast put in new Modem/Router with WiFi

* moved original SonicWall TZ300 to new building

* did not bring the Access Point (A/P) with move

SonicWall setup for DHCP; had Comcast turn off DHCP on modem but leave WiFi available.   However, the laptops are not getting a DHCP address from the SonicWall (SW does not have WiFi).   The Comcast WiFi doesn't use the on premises DHCP?

Is there a easy work around or do I need to get a access point for wireless devices?   Was trying to use the Comcast WiFi to save cost and one more device.

Thanks,

Darryl