Yealink T26 and is not accepting Option 66

[jolouis]

Check under Settings->Auto Provision and make sure that "DHCP Active" is set to "On". Without that the phone will ignore the DHCP options and not provision using that method.

Alternatively do a complete factory reset of the phone (hold the OK button for 10-15 seconds until prompt on the screen shows up) just to be safe. We have provisioned many T26s back when they were an active product using DHCP/TFTP, so definitely not a problem with the phones in general...