New WS-12-DC doesn't forward packets

[rrobinet]

I am staging a WS-12-DC to replace an in service WS-6-MINI. Both are running in factory default mode, even with the factory addresses 192.168.1.20.
I have two laptops attached to the WS-12-DC with static addresses 192.168.1.21 & .22 and both laptops can ping the WS-12-DC and open it web pages, but they cannot ping each other when connected through the WS-12-DC. They can
The WS-6-MINI connects the two laptops without any configuration changes. Is there some configuration needed for the WS-12-DC for it to act as a simple ethernet switch?

[lligetfa]

Was the switch shipped with 1.55? There is a known issue with switches that were born 1.55. Upgrade to 1.56 or reflash 1.55.

[rrobinet]

Thanks, but I just upgraded to 1.5.6 and have the same problem.
I don't know where to find the SW version on the working MINI.

[rrobinet]

But reflashing with 1.5.5 got my switch working.
Thanks for the help.