Some connection trouble with RB250

We purchased some RB250 switches, installed a couple of them to our clients. But recently we’ve tried to connect to another RB250 and found, that its first port could not establish connection with an RB411 device at 100FD FastEthernet speed. The only way to get it connected through 1st port is to force them both to connect at 10M speed. Another ports are working normally.

This was encountered with 3 another switches from the same package. What is the matter and how to get them work on 100M speed?

What SwOS version are you using? Are all ports affected?

SwOS version is 1.2, but that’s not a matter - the same was seen with SwOS v1.0. Only the 1st port is affected

are you using POE?

No, PoE is not being used.