Multiple virtual NICs for VLANs


Mar 30, 2020

i'm reconfiguring my home network in order to seperate different devices via several VLANs.
Unfortunately some devices need access to multiple VLANs at the same time.
Since i am using just layer 2 switches and i dont want to hammer the routing between the VLANs on my Unifi USG Pro i thought i simply add a virtual NIC per VLAN to my Windows Server VM.
Unfortunately after some speed tests i noticed that speed only increases to full 10gb when i disable the NIC that is not needed right now.
For example:

NIC 1: (VLAN 10 tag)
NIC 2: (VLAN 20 tag)

I want to download a file from When both NICs are enabled I get arount 80MB/s. When disabling NIC 2 i get full 10Gb speed.

Maybe i'm wrong, but shouldn't be routing traffic from VLAN 10 to VLAN 20 become obsolete when the device is in both VLANs at the same time?
I'm using a single bridge that is VLAN aware on a 10Gb port

From point of view of you windows server, both NICs in one network. You must use different NETs for NICs, like,
I think, in your situation better use different NETs for separate you devices. Because in both configurations - vlans or different NETs, you need router between vlans or NETs. You switches L2 and can't route traffic between vlans.
On you server (or another device, then must accessable in both NETs), you can use one NIC with two IP.
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