Yealink T26 and is not accepting Option 66

[SimonVolk]

Hi All,

I am experiencing some issues with Yealink devices T26 and T29P in combination with DHCP option 66.
Other models are working fine such as T22 T28P so I think that the server configuration is correct.


Scenario:
During boot process the T26 requests the IP address from the DHCP (isc-dhcp-server), in the response the DHCP sends the TFTP Option 66 to the device (answer displayed below).


The problem is that the T26 does not accept the parameter and it does not starts with auto provisioning. In the GUI the Server URL field is empty.
Does anyone know where is the trick ?
I already tried to change few SW releases but i got always the same result.
Any help will be appreciated.



kubuntu.bootps > 192.168.10.12.bootpc: [udp sum ok] BOOTP/DHCP, Reply, length 300, xid 0x76949562, secs 100, Flags [none] (0x0000)
Your-IP 192.168.10.12
Server-IP kubuntu
Client-Ethernet-Address 00:15:65:21:21:cb (oui Unknown)
Vendor-rfc1048 Extensions
Magic Cookie 0x63825363
DHCP-Message Option 53, length 1: ACK
Server-ID Option 54, length 4: kubuntu
Lease-Time Option 51, length 4: 40114
Subnet-Mask Option 1, length 4: 255.255.255.0
Default-Gateway Option 3, length 4: kubuntu
Domain-Name-Server Option 6, length 4: kubuntu
TFTP Option 66, length 22: "http://10.10.10.10/ps"
END Option 255, length 0
PAD Option 0, length 0, occurs 2


Thanks

Simon