I have these brand new MS390 switches that I want to uplink to the Distribution switches. I have installed the 2x40G QSPF+ modules and they work when connecting 2 MS390's together but when I connec them to the MS450 that ports stay in the disconnected state.    The config on both ends is default. I have a 40G QSFP+ cable and they both indicate in the syslog that the port is up but stays in a disconnected state. On the MS450 syslog shows the cables is connected, the port is up and it is running at 10G On the MS390 syslog shows no change in status.   I have multiple MS390's and MS450's and have tried on all of them and get the same result. There must be something I am missing with these.   Cables uses are MA-CBL-40G-3M   I have the MS450's stacked together I have 3 sets of MS390 is 2 pair stacks. The uplink issue exists with or without the stacking on all switches. I can connect to the MS390 copper ports and access the switches so I know they do work...sort of! ... View more