What exactly does OPNsense show you as the interface speed?
I have OPNsense running on Proxmox VE and it shows "10Gbase-T <full duplex>" on all interfaces.
I also have one OPNsense VM running on ESXi 6.7 U3d, but can't access it right now (it also uses VMXNET3 NICs).
If you use the Intel E1000e NICs for your OPNsense VM, they will be limited to 1Gbit/s btw - make shure to use vmxnet3.
I have OPNsense running on Proxmox VE and it shows "10Gbase-T <full duplex>" on all interfaces.
I also have one OPNsense VM running on ESXi 6.7 U3d, but can't access it right now (it also uses VMXNET3 NICs).
If you use the Intel E1000e NICs for your OPNsense VM, they will be limited to 1Gbit/s btw - make shure to use vmxnet3.