Hi, Good to hear GTAC is already involved.
While waiting for their feedback, I'd try to determine whether the issue is related to Option 150 or to the DHCP service itself. One quick test would be to create a basic DHCP pool in 9.4 without Option 150 and see if clients can obtain addresses.
I'd also take a look at the DHCP statistics and leases (show ip dhcp-server statistics and show ip dhcp-server leases) to confirm whether the switch is receiving DHCP requests and attempting to respond. Comparing the outputs of show ip dhcp-server, show ip dhcp-server pool, show vlan, and show ip interface between the working 9.2 configuration and the 9.4 configuration may also reveal something subtle.
If possible, I'd verify whether the behavior affects all clients or only Cisco phones. My feeling is that if devices are not receiving an IP address at all, the issue is probably occurring earlier in the DHCP process. An Option 150 problem would normally affect phone provisioning and TFTP discovery, not basic address assignment.
Hopefully GTAC will find the root cause quickly. Please share the outcome when you have it, as it could help others running VOSS 9.4 with DHCP services.
