Welcome to the Community,
I assume that the ESXi hosts are connected to tagged (802.1Q) physical switch ports, the VLAN has already been created/configured on the physical switch(es)!?
In this case you may simply create a new port group on the vSwitch with these uplinks, and set the VLAN-ID for this port group to 900.
Thank you so much for your reply, if you don't mind we are using VMware vSphere 6.7 and it would be very much appreciated if you could give a step by step process. I'm still new to virtualization.
Again thank you very much...
I've 2 servers that are running ESXI (Raid 5) and one Vcenter server, all have 4 nics.
In order to help, I need to understand your current setup.
Please post the configuration for the physical switch ports to which the ESXi hosts are connected (especially the VLAN configuration).
In addition to the physical details, provide some details about the current virtual configuration, like Standard vSwitches or Distributed Switches, uplinks (vmnics) connected to the different vSwitches, existing port groups, ... (some screen shots would be useful).