Hi, I´m a really unknown user of networking and just thought, it´s easy to upgrade my system with 10Gb SFP+ for more speed. So I bought one CRS305-1G-4S+. Here is my basic server und workstation farm:
AVM FritzBOX 7490 with DHCP server und Internet connection as main router. Than a 16port 1Gbit Switch. I run a Win10 Laptop with 1gbit, some LAN hardware like printer, NAS and so on. Now I have two Servers with VMWare ESX and each running a Windows 10 pro x64 VM system. Basicly I have installed on both Servers a dualport 1GBit card. All runs fine. Now I installed in each server a 10GBe SFP+ Dualport card and bought one CRS305-1G-4S+. I connect the SFP+ to the switch. The new SFP+ cards are plugged in to my VM system as the main card and the 1GBit as failover. All is installed with static IPs and connected to the Gateway adress of my FritzBOX Router with right masking 255.255.255.0 and DNS Server.
I can copy now files from one Server to another and from my Laptop (connected to the 16port switch). But: I´ve got no internet connection on my VM Windows image? Unless I disconnect the CRS305-1G-4S+, the VM get´s the connection from failover 1GBit port, which is connected to the main 16port switch. (this is a unmanaged switch from TPLink).
By the way: The WAN/Ethernet port of CRS305-1G-4S+ is also connected to the 16port switch. This is a really cheap setup. But it works without internet.
I´ve running the CRS305-1G-4S+ as SwOS 2.1 and also tried RouterOS 6.46. All with latest stable firmware. Both are working. I setup these with static IPs and gateway. I can download the firmware inside the web GUI. But when I start my virtual machine, I won´t get an internet connection.
Sorry, but I´m not confirm with VLAN and so on. So please give me an detailed advise 
But: I´ve got no internet connection on my VM Windows image? Unless I disconnect the CRS305-1G-4S+
Did you configure the VMs on your ESXi server to use the SFP network ?
Did you made the appropriate configuration in the ESXi network management ?
Does the SFP card in your server get an IP?
Did you configure the VMs on your ESXi server to use the SFP network ?
- Yes, I build a new vSwitch called “v10GB”. And a port group “VM Network” asign to this v10GB. Inside the v10GB there are the SFP uplinks.
Did you made the appropriate configuration in the ESXi network management ?
- what do you mean with appropriate config?
Does the SFP card in your server get an IP?
where can I set it?
To make it simple, can you see an IP assigned to your SFP adapter through your DHCP server ?
If not, check again the TCP/IP settings of your network card in the ESXi network settings…
By default DHCP client is enabled in the TCP/IP settings in the ESXi, so if no IP is assigned check your settings again…
Those settings are inside the VMkernel, although those settings can be skipped…
Most important, do your VMs have selected the newly created VM network ?
Inside the VMKernel is a TCPIP/Stack IPv4 192.162.196.1 and subnet 255.255.255.0. This is in VM Management. Inside the VM machine (Windows) there is a static IP asigned to the ethernet VMXNET3 port like 192.162.196.20/255.255.255.0 and Gateway/DNS to 192.162.196.253 (the fritzbox IP).
One thing: I rebuild my RouterOS by default config with a DHCP Client on bridge and all ports inside the mikrotik are a part of this bridge. I got an IP from my fritzbox. this works.
Now I startup my ESXI and I´ve got one vSwitch0 with the managment and vCenter inside. The management VMKernel port is also asigned to the vSwitch0. Now I build a second switch called 10Gbit and asigned the 10GB uplink adapter to this and also one failover 1Gbit from my motherboard if the 10GB have an error. In this 10GBit is the VM Network asigned to get full speed. But, must a create a second VMKernel for this 10GBit vSwitch? With a second IP?
The mikrotik won´t work with one vSwitch and the second vswitch.
I can ping the kernel IP of ESXi system (192.168.196.1)