CRS312-4C+8XG-RM Slow Speed / can’t change to SWOs

Hello Guys,

i hope someone can help me.
I have a CRS312-4C+8XG-RM Switch for 2 days and i had some Problems.

The Switch has the default Settings as Bridge but the Performance Is not very Good.
This Is the main Problem.
The Speeds Is like 5gigabit.

I have tried to set the mtu to 9000 (Jumbo Frames) on the Interfaces but this did not help.

The Switch is for the Connection of my nas to my Other 10 gbe devices

I have one cable direct attached with icsci to my Server and there i had 10 gb Full but the Connection from the Switch is under the half

I think it Is the Bridge function which makes it slow.

I read in a Other Thread i should change to the SWOS
Correct me if i‘m wrong.
The bridge Function makes to much overhead
to be so fast as the Switch.

So i Look How to change the Router to Switch os but i had not the opinion under System → Routerboard > Settings

Then i try the command:
/system routerboard settings set boot-os=swos
The system recognize the Command but nothing happend
I Boots to the Router os like before.

the product Page says i can Use a Router os or a Switch os

On the end of this SWOS wiki are some serial commands
Should i buy a usb to serial cable to change the Router os to SWOS ?
https://wiki.mikrotik.com/wiki/SwOS/CRS3xx


Did anyone have a idea ?

It’s a bug in the software/firmware. Contact support.

ok Thank You.

I will try to reach the support.
I tried to reinstall several older versions of the router OS, but that didn’t help.
I used the netinstall tool.
Maybe this tool has a bug too.

No, it’s the software/firmware. For some reason the released version doesn’t recognize the dual-boot nature of the switch, apparently.

Support supplied me with updated beta software. After updating the software and firmware, the options appeared in Winbox and the CLI to change the boot OS, and I’m running my switch in SwOS now.

OK Thank you for your help

I will write the Mikrotik Support directly because my my local seller can’t help me.

Did you call the technical or Hardware Support ?

Submit a ticket online through your Mikortik account.

I made a Ticket
I hope they’ll averring me because i bought the switch by a local dealer (Reichelt Elektronik Germany).

Thank you for your help.
In Case they refuse my Ticket.
Could you upload the file in a zip ?

That would be nice

They won’t refuse it. It doesn’t matter where you bought the switch.

I will not upload the software. It isn’t publicly available, and I believe they have the right to control how it gets distributed. It sets a bad precedent.

I Hope so.
i really like that Switch and the Switch OS can in increase my Network Speed instead of the bridge mode which is default configured.
It should be faster when he Acts as Layer 2 Device.

No Problem
I don’t want you to have any legal problems because of that either.

I’ve discovered something else after a little experimentation. It seems the specific issue is with the firmware. I left the firmware at the version provided by support but downgraded the software back to 6.47.8, and the “Boot OS” menu appears in the RouterBoard settings again.

Very Interesting.
I will do some Experiments when i get the Firmware too.

Are you happy with the Performance of the Switch with the swos.

I can’t wait to test the speed with the Switch Os.

As it turns out, though the Boot OS selection is available with current software and updated firmware, it doesn’t function. Rats. You have to have the sw and firmware both at the beta version for it to function.

That said, I’m not really pushing this switch very hard, so I can’t really comment on the speed. It’s always performed well for me for what I use it for.

I have this exact same problem, too. Brand new CRS312-4C+8XG and the menu option is simply missing to change the boot-os.

Opened a ticket with support. Hopefully they can sort me out.

This is fixed in the current testing version (6.49beta11). It’s listed in the release notes.

Support responded to me and told me to install v6.48.1. I did that, saw the reboot option to SwOS, selected it, and rebooted.

Now the device is stuck in what appears to be a bootloop.

  • All the lights on all ports turn on and blink for ~3 seconds.
  • Fault light (red) turns on briefly
  • Port lights turn off for ~10 seconds. Power light remains on.
  • Repeat, forever

The device no longer appears in WinBox at all, I can’t ping it, and it’s completely inaccessible. So now I’ve got a loud paperweight. Ugh.

Maybe it’s got an old version of SwOS on it? But fixing that would probably require me getting back into RouterOS, which I can’t do because I’m stuck in a bootloop. Is this something where I should do a factory reset by holding the reset button while powering on? Did I do something wrong when upgrading? (I grabbed both the main + extra RouterOS packages from the download page)

A serial console cable is probably your best bet at this time. You should be able to get to the boot loader and choose routeros.

I got a serial console cable over the weekend, switched to RouterOS, manually updated, and got everything running. Thank you everyone for your help.

For anyone else who might buy a new CRS312-4C+8XG-RM and want to use SwOS, here is the step-by-step. I hope it helps someone else avoid the frustration that I experienced.

  • Grab WinBox from the Mikrotik download page (https://mikrotik.com/download).


  • Manually set your computer’s IP address to 192.168.88.2


  • Plug in an ethernet cable to your PC and the device. Use WinBox to connect via port 192.168.88.1


  • Update RouterOS to v6.48.1 (https://mikrotik.com/download). Be sure to get both the main + extra pacakges. Instructions: https://wiki.mikrotik.com/wiki/Manual:Upgrading_RouterOS#Using_Winbox


  • Reboot the device.


  • Don’t change the Boot OS yet! You’ll get stuck in an infinite boot loop! If you do make that mistake, you’ll need a USB-to-RJ45 serial cable that you can access the console and switch back to RouterOS.


  • Connect a port on your device to your existing network switch.


  • In RouterOS, add a DHCP Client (Dynamic IP). (https://help.mikrotik.com/docs/display/ROS/First+Time+Configuration)


  • Wait a few seconds, and then verify that you are connected to the Internet. Open the command line interface and do a ping test. E.g. 8.8.8.8


  • On the command line interface, update SwOS with the command:
/system swos upgrade



  • Wait for the update to finish. It only takes a few seconds, and you’ll get a message displaying the new version of SwOS.


  • Reboot RouterOS


  • In RouterOS, note the SwOS IP address. I didn’t need this because it picked up an address from my local DHCP, but I suspect it doesn’t pick up an IP address then you’ll need it. Mine defaulted to 1.88.168.192
System ==> SwOS ==> Static IP Address



  • Change the BootOS to SwOS.
System ==>RouterBoard ==> Settings ==> Boot OS



  • Reboot the device.


  • Change your computer’s IP address back to automatic.


  • Your device should get an IP from your DHCP server. Check it to find the IP address. Connect to that in a browser.


  • Default login is admin with no password.


  • Change the password (System tab)

If you want to go back to RouterOS, there is a button on the bottom of the System tab.