Yealink T54W Auto Provision not working

[h.cmc]

Hi all,

Hoping someone can help clear this one up for me as I'm a bit stumped what's going on here. I have 2 networks running in parallel:

1 - Legacy network. With a bunch of SIP-T54W phones operating just fine. DHCP server is Windows Server with option 66 and our 3CX http URL defined.
2 - New network, separate WAN link. With an SDWAN appliance acting as DHCP server, and scope option 66 copied from network 1 and confirmed against our 3CX server's auto-provision settings. Phones can successfully resolve the 3CX server hostname.

Wireshark on the SDWAN appliance and switch shows that the DHCP server is offering the correct settings, including the URL via 66. However, I do not see a DHCP Inform from the phone. If I remove option 66 from the configuration, Wireshark shows that the phone successfully sends out DHCP Inform.

With 66 defined, logging in to the phone and the auto-provision URL is blank. DHCP is on. Factory reset the phone, same results.

If I configure scope option 132 with our voice VLAN ID, the phone successfully moves to the VLAN and refreshes its IP. So the phone is definitely picking up some of the DHCP options. For now, I am leaving out 132 and just trying to get the phone to auto-provision on our default VLAN to keep it simple.

See attached images for captures. Any assistance is greatly appreciated.