Hi,
the blue LED of that switch is partly annoying since this switch is not installed in a rack but on the wall to adapt a fiber to RJ45.
Since it uses SwOS lite there no setting to switch off any LED or dimm it.
Does anyone have an idea how to dimm or switch them off?
Thanks
Insulation tape, pick your favorite color.
Or ( common PVC insulation tape adhesive tends to smear over time), dedicated stickers (hopefully with more stable adhesive) do exist, google for “LED Light Blocking Stickers” or “LED Light Dimming Stickers”
Ok, there is no other possibility then putting a sticker in top? Strange…
Or can the be installed routeros which might provide a certain switch to do it?
sure there is: use a paint marker pen! That’s the proven solution since the first red LEDs appeared.
You can solder a pull-down resistor to the led to dim it, or replace the led with an infrared one 
(it sounds stupid, I know 
, but usually you can see infrared led activity through your smartphone camera, so you would still be able when needed to check what happens).
Thanks for your suggestion. But open the device solderinrg whatever (cause its SMD and won’t be that easy…) I still might make use of a sticker.
A change to Router OS isn’t possible? There was no answer to this question yet…
No, on CSS devices SwOS is the only option. Main difference between CRS devices and CSS is that the later lack general-purpose CPU (and storage and RAM), capable of running a more complex OS (while L2 capabilities may be similar in both cases).
… and has potential of dammaging your retina because failing to see LED’s activity increases probability of looking directly into it.
Q.E.D.
Sure, lots of people became blind by staring at surveillance cameras at night and trying to visually check if their TV remote was working, it can be extremely dangerous. 
CSS610 is practically the simpler of the switches Mikrotik currently Have (from management/control plane perspective), it does not support even regular swos, instead of this was necessary to use swos lite on it.
RouterOS is a system with more features but it requires some minimum resources of CPU, RAM and Storage to operate, which a simple device like CSS610 simply does not meet, not even close.
on a device like CSS610 all the packet/frame forwarding is done by the switching ASIC, thats its purpose and is good enough to accomplish this duty
Thank you for explaining the specialities of the CSS610.
For the duty of converting fiber into copper and feeding just a WAP ii’s good enough, that’s right,
but this led is a bit to light and I put a small sticker (VHB band of 3M) which cover and supress the light.