In this article, we will explain how to perform a Netinstall on a MikroTik RouterBOARD with or without a serial port.

Netinstall using a RouterBOARD with a Serial Port - Start at Step 1.
Netinstall using a RouterBOARD without a Serial Port - Start at Step 4.

Step 1:
Download PuTTY SSH and Telnet Client:

Step 2:
Configure PuTTy for MikroTik Serial Console access (Ensure you select the correct COM
port for your serial port - you can find this under the "Ports" section of your "Device Manager" in Windows).
Serial line to connect to: COM1 (Serial Port found in Device Manager)
Speed (baud): 115200
Data bits: 8
Stop bits: 1
Parity: None
Flow control: None

Step 3: 
Plug your serial cable into your RouterBOARD. Click open in PuTTy then power
on your RouterBOARD. You only have about 2-3 seconds to hit any key to enter
the RouterBOOT Menu so be quick!

Step 4 - (No Serial Port - Start Here):
Download the RouterOS Upgrade package and corresponding Netinstall files from the MikroTik Website (I have chosen the latest version as of writing v6.46):

Step 5:
Extract and Run Netinstall and select ‘Net booting’. Enable the boot server and give it an
IP Address on the same subnet as your PC / Network.

Step 6:
Connect the RouterBOARD Ethernet port 1 to your PC / Network. Ensure your PC has a static or DHCP address on the same subnet as the Boot Server configured above. i.e.

Step 7 (Serial Port - Skip this Step):
Hold the reset button whilst applying power to the Router.
Release the reset button when the ‘ACT’ led goes out (it will flash for a while
the go out). A few seconds later you should see Ethernet port 1 led come on
and your device will show up in Netinstall.

Step 8 (No Serial Port - Skip this Step):
Issue the following in the Serial Console RouterBOOT menu:
Press "o" - boot device
Press "1" - boot Ethernet once, then NAND
Press "x" - exit setup

Step 9: 
Browse to the folder location of your "routeros.npk" package downloaded in Step 4.

Step 10:
Select your router in the list and then choose the RouterOS package
you have downloaded and click "Install".

Step 11:
Once the Netinstall has finished click "Reboot" (if this is greyed out the router has automatically initiated the reboot process.