I'm trying to change the VM's adapter from E1000E to VMXNET3 however in edit sections from vCenter does not allow me to change it, and if I create a new adpater it doesn't show it as an option
These may help:
Looking to the name of the VM i assume its a virtual ESXi? Yes i read about that that you can use VMXNET3 for a ESXi VM but i dont remember any details because i dont have a need for.
You can change this directly from the ESXi host web interface when the VM is power-off, or via modifying details of the VMX file, associated with that VM.
You cannot change the Type of the NIC in the GUI. Here you can only delete it and add a new one with the correct type but this will also genereate a new MAC Adresse for your VM. For changing the NIC Type and preserve the MAC Address i always use PowerCLI/PowerShell -> PowerShell Gallery | VMware.PowerCLI 22.214.171.12447286
Open PowerShell and install the PowerCLI Modules:
Install-Module -Name VMware.PowerCLI
Now you can connect to your vCenter with:
Connect-VIServer -Server yourvcenter.fqdn
And change the NIC Type of your VM (the VM must be PoweredOff) - in your case:
Get-VM -Name SDWAN_vESXi | Get-NetworkAdapter | Set-NetworkAdapter -Type Vmxnet3
Hope this helps a little bit