ethernet problem between to RB 433

Hi all,

I have the following setup:
1 RB-433 running OS 4.3 (A)
1 RB-433 running OS 3.30 (B)

They are both connected via short cable on ether2 on each board.

Problem comes when I upgrade router B to version 4.3.
The ethernet connection gets established but traffic cannot go through even simple ping on the interfaces.

I tried all combination of ports (and link speed and duplex mode) and it shows the same behavior.
As a final attempt, I downgraded router B to 3.30 and voila the connection is established and traffic is back to normal.

Has anyone run into the same/similar problem?
any suggestion is appreciated.

Thanks

There is a bug with ether2 and ether3 not working correctly on some RB433 in v4.3. This bug is fixed in latest v4.5.