W5500 Fails at -20 Degree Celcuis

TCP/IP Chip W5500
1

Hi,
I am using W5500 in one of my product and recently tested its negative temperature. Below -20 deg cel the W5500 stoped working despite its datasheet mentions working capability of upto -40 deg cel.
I need guidance from Wiznet community, otherwise i have no option but to switch to another ethernet IC.

Thanks.

2

How it fails? How it stops working? Any diagnostic information?
Edit: circuit has some more components than W5500, maybe something else is a cause, for example crystal?