Yealink T46S refuses to upgrade from 66.83.0.55

[dkdocks]

Commanding the phone to re-provision (works) via 3CX phones tab.
Commanding the phone to reboot remotely (works) via 3CX phones tab.
Asking the phone to upgrade from (3cx 66.83.0.55 ) to 66.86.0.5 (3CX v18 Alpha-5 Hosted) does not work at all.
This remote users phone dislikes me, any advice aside from asking the remote user to re-flash the phone via his browser is appreciated.
Phone just reboots into 66.83.0.55 (Unsupported) and laughs in my face, any ideas welcomed.

Thanks kindly as always for any input.

 

[NickD_3CX]

Hi there!

Please read the note here:
https://www.3cx.com/sip-phones/yealink-t4-series/#h.7ls0w5vyhlnd

You are on quite an old firmware version and you manually need to first upgrade to an intermediate firmware, before going to the latest.