1616 Phones are stuck on https://@:411

[cisternejp]

Hello,

I have a strange issue with two of my customers using 1616L IP Phones.
They are running IP Office Server 9.1.8 and the second one 10.0.3.

When the phone reboot, sometimes the phone is stuck and the screen is displaying HTTPS:1 https://10.1.122.120:411/16xxupgrade.txt

I have to reboot it several times to download the file.

I made the following tests but the issue still happen:
- Rebooted the IP Office Server
- Downgraded and Upgraded the phones
- Changed the 16xxupgrade file in the IP Office Server.
- Double checked if I can download the upgrade file from a computer with https
- Regenerated the IP Office root certificate.

Does someone have an idea how to fix it ?

Thanks for your help