Potentially a port issue on the WiFi Vlan?

Check your DNS settings on WiFi versus Ethernet. Could be a DNS resolution issue resulting in the iPads cannot reach the Jamf server.

Or like AtillaTheC said, it could be a network port or restriction issue too.

Thanks for the replies, interesting issue where the DNS settings on the iPad (when on wifi) don't have the Search Domains area populated, but it is in there when I check the same setting on the ethernet connection. DNS servers ip's are populated and are the same on wifi and ethernet. I'll keep digging!

After much digging and testing, found that a previous employee had added a firewall rule blocking JAMF communicating with the generic account being used by the iPads. Removed the rule and iPads are now updating.