Yealink W52P: Not able to upgrade handset through web interface

[Igor_]

I have the following W52P device:
Base:
- Firmware Version: 25.81.0.10 (latest, I did upgrade)
- Hardware Version: 25.1.0.0.0.0.0
Handset:
- Firmware Version: 26.73.188.2
- Hardware Version: 26.0.0.10

I have managed successfully to upgrade base firmware through the device web interface with the file: “Base for W52P&W56P-25.81.0.10.rom”

When I try to upgrade handset firmware W52H-26.81.0.30.rom (from device web interface), I receive popup “Handset Firmware of the SIP phone will be updated. It will take 5 minutes to complete. Please don't power off.”

I click OK.
Page web GUI says:

Handset Firmware Updating ...
Please wait and do not power off!
And the browser must not be closed or refreshed!

Base will reboot, however handset will not get new firmware. Even if I try to restart the handset.

Is it possible to update W52H through web interface? Or web GUI update option is only for W56H taking into account that the base firmware (and web interface) are the same for W52P and W56H?

Many thanks,
Igor