Question: I am trying to migrate both the only vCSA and the VMKernel interface in my ESXi host from a standard vSwitch to a vDS, and that gave me all kinds of mess. How to do that properly? Bear in mind that the host in question also have the virtual machine that performs as the router.

My intended setup:

The host:

```
                     [      ]- vmnic0 -+- LACP --- Switch 1 (managed)
Internet --- vmnic3 -[ Host ]- vmnic1 -+
                     [      ]- vmnic2 --- Switch 2 (unmanaged)

```

vSwitch0:

```
vmnic3 --[ vSwitch0 ]-- vRouter

```

vDS:

```
vmnic0 -+- LAG1 --[     ]-- vRouter
vmnic1 -+         [ vDS ]-- vCSA
         vmnic2 --[     ]-- vmk0 (management network)

```

vRouter (OS: Ubuntu Linux):

```
vSwitch0 --[ vRouter ]-- vDS

```

vCSA (and other VMs):

```
vDS --[ vCSA ]

```

Other physical computers are attached on `Switch1` or `Switch2`. There is also another ESXi host.

Answer: 
I don't follow your question very well, but I will make a suggestion all the same.

If VC looses network connection during a network reconfig, the change is automatically reverted (sometimes), even if it is only for a moment.

I would suggest putting your VCSA onto a temporary second network (so you have two routes), this way you can stop using the primary net while you do the moving around.
I think you should migrate in two steps, first to a vDS without LACP and then enable LACP. The first step should be straight-forward: Create the vDS and port groups you need and set vmnic0 as the first uplink and migrate your vmknics and vCenter to the vDS. Then set vmnic1 as the second uplink for your vDS. Then [migrate to LACP](http://pubs.vmware.com/vsphere-55/topic/com.vmware.vsphere.networking.doc/GUID-45DF45A6-DBDB-4386-85BF-400797683D05.html).

I've stumbled on an interesting blog posting recently: [Disabling vSphere vDS Network Rollback](http://vwud.net/2016/02/16/disabling-vsphere-vds-network-rollback/). Maybe this can help you, too.