2716 hangs when on UPS power supply

Hello!

Our Powerconnect 2716 hangs as soon as UPS switches to emergency power supply.

Tested 3 different UPS's (APC Smart-ups 1400, APC 700, Fiedeltronik Ares 3000)  - no difference.

Also tried connecting a dedicated UPS for 2716 - no difference.

Any other devices connected to these UPS-es work fine when on emergency power supply...

I run out of ideas... Anybody encountered problem like this?

regards

Tom