The only instruction I found is outdated and not working for me, (luck of experience probably).
When I set VLAN-90 Management Enabled and VLAN-1 Disabled it nothing happens, set port 1 to Trunk what connects to the NSE make no different, changed IP Routes Override to the gateway address of VLAN-90 still no change, management ip always from VLAN-1, after changing various other related setting the switch loose cloud connection than reload old config after 15min. Is there a newer doc for cnMAestro 5.1.1 ?
I guess this is much harden than its should be, 3hr remote session with support still can’t make it work.
Now it’s not even a question why do I want VLAN-90 as a Management VLAN, the question is why do I loose cloud connection if I add or even just enable another VLAN with management support ON.
The engineering team has indicated that the issue seems to be related to MTU size, which has been resolved in version 5.0.3, after updating it to 5.0.3 I was able to assign VLAN90 on port 1 to management…
I’m so relieved and pissed in the same time, I we have plug in the uplink port to anything but port 1 & 25 it would of worked 2 days ago 
5423 EX3052RP/EX3028R-P MTU Incorrect default MTU setting on ports 1 & 25 on EX3052R-P, and port 1 on EX3028R-P cause tagged frames to drop