Two network cards: SMB (file share) connecting to wrong IP

Question

Hi,

The situation:

When a server is having two network cards, client tries to connect to secondary IP through gateway(firewall).

I can access the file share but trying to connect wrong network card will create timeouts because there it is wrong route.

This is how it should go without going to gateway, because they are in the same subnet.
Source 10.0.0.50 -> Destination: 10.0.0.49:445 (SMB).

This how it sometimes tries to go:
Source 10.0.0.50 -> Destination 192.168.0.15:445 (SMB)

Server: Windows Server 2016 (1607)

Network adapter 1:

IP: 10.0.0.49
Mask: 255.255.255.0
GW: 10.0.0.1
DNS: 10.0.0.21

Network adapter 2:

IP: 192.168.0.15
Mask: 255.255.255.0
GW: None
DNS: None

Client: Windows Server 2016 (1607)

IP: 10.0.0.50
Mask: 255.255.255.0
GW: 10.0.0.1
DNS: 10.0.0.21

I have tested with Server 2022 and Windows 10. It is the same situation.
If any would have some solution or hints, I would be grateful :)

BR,

Mr. Roska

Answer 1

I found the reason. By default Windows uses MultiChannel. It is good for load balancing but when having network cards on totally different networks it can be disabled:

Set-SmbServerConfiguration -EnableMultiChannel $false