T46g & T48G RADIUS 802.1x and SHA256

Hi Guys,

In the past, the RADIUS Authentication 802.1x worked beautifully with the Yealink T46g & T48G Phones.

Now we create a new CA Root Certificate.
The old certificate was encrypted with SHA1 and that new with SHA256.
Since the authentication stops working.

On the phones is the latest firmware 30.80.0.95.
CA Certificate = SHA265, 2048 bits, BASE64 export.

Is there not SHA256 encryption support for 802.1x by this Phones?

Thanks for the help,
Torsten