Disabling VTP stops DHCP

I have run into a problem with a network I am currently working on and do not understand why this is happening. I am attempting to remove VTP from the network and running into a problem where DHCP for wireless access points themselves is failing whenever I try. The setup is as follows:

DHCP Server for WAPs ----- Cisco 2960X +++++ Cisco 3850 +++++ Cisco 2960X ===== WAP XXXXX ----- switchport mode access switchport access vlan 70 +++++ switchport mode trunk switchport trunk native vlan 10 ===== switchport mode trunk switchport trunk native vlan 70 switchport trunk allowed vlan 70,90 XXXXX Where I am disabling VTP: vtp mode off VLAN 10: management VLAN 70: wireless ap management VLAN 90: wireless users 

From what I can tell, whenever I turn off VTP on the switch marked below with XXXXX, DHCP requests do not make it to the DHCP server, which is a firewall and happens to also be the gateway for VLAN 70. There is no SVI for VLAN 70 in the Cisco 3850, but adding one, even with a helper-address, does not resolve the problem.

I am thinking I just need to just use another DHCP server we have running on the campus, instead of the firewall, and put the default-gateway as an SVI on the 3850, but still do not understand why turning off VTP on that switch causes this problem.

Does anyone know what I am missing?

Thank you for taking the time to read and inform, it is most appreciated.